hooberus....I was not necessarily referring to the present text of Luke or John but more specifically to these stories or episodes as blocks of tradition, either oral or as written sources incorporated by the gospelists. Luke depended on earlier sources (cf. Luke 1:1-3), and the Emmaus episode in Luke 24 is unique to the gospel and thus represents Luke's special source (L). I was not necessarily arguing that Luke 24:33-49 was non-Lukan (or John 20:20-29 as post-Johannine), but only that at some point in the transmission of the tradition the two episodes narrated in Luke 24:33-49, emphasizing Jesus' corporeality, were added to mitigate the quasi-docetism latent in 24:30-31. Your appeals to P66 and P75 pertain only to the present text of Luke, or rather, the form attested in the early third century when these manuscripts were copied. There is overwhelming internal evidence (cf. Koester's Ancient Christian Gospels for more info) and external evidence (cf. Secret Mark, the "common omissions" of Mark in Matthew and Luke, the early gospel harmonies, patristic quotes, etc.) that the gospels underwent redaction and revision in the second century, so that Mark went through several editions, John was significantly interpolated and disordered, and so forth. But since the earliest manuscripts for these gospels either postdate these alterations or do not represent the portions where they occurred, the papyri are of limited value in detecting such early developments (just as the Dead Sea Scrolls are too late to attest a version of Isaiah without the Deutero-Isaiah additions). In the case of Mark, we are lucky to have the two witnesses of Matthew and Luke which attest the late first-century text of Mark -- long before the earliest available papyri texts.
The evidence in this case is mostly internal. The narrative in Luke 24:30-31 is quasi-docetic because of the use of the adjective aphantos "invisible" + the verb egeneto "became". This verb implies that Jesus did not merely leave the room unseen (such as while the disciples were distracted) but became invisible, or unseen, as a change of state. The adjective is a hapax legomenon in the NT and to my knowledge it is absent in the LXX as well. It does have a well-established usage in Greek writings, referring to the supernatural vanishings of gods, demigods, and so forth -- especially with the verb "become". Thus we read in Diodorus Siculus: "And Dionysos led Ariadne away by night to the mountain which is know as Drios; and first of all the god (ho theos) vanished (éphanisthé), and later Ariadne also became invisible (aphantos egenéthé)" (Bibliotheca Historica 5.41.4-52.1; cf. 3.60.3, 4.82.6). Cf. also Euripedes, Hercules 873, and Apollonius of Rhodes: "Thus they spoke and with the voice vanished (aphantoi) at once where they stood" (Argonautica 4.1330). In Christian writings, the expression when it occurs is used typically of spiritual beings like demons:
"And the apostle said: They also shall now be abolished, with their works. And suddenly (aiphnidiós) the demons (hoi daimones) vanished away (aphantoi gegonasin): but the women lay cast upon the earth as if were dead, and without speech" (Acts of Thomas 77:13).
"So looking up he saw the roof as it were opened, and a ray of light descending to him. The demons (daimones) suddenly vanished (exaiphnés aphantoi gegonasin), the pain of his body straightway ceased, and the building was again whole" (Athanasius, Vita Antonii, 26.860).
Note also the occurence of "suddenly" in these texts to emphasize the notion of a sudden disapperance. Luke 24:31 does not highlight the time aspect but makes clear that Jesus "became invisible" while "they recognized him" (epegnósan auton), while their "eyes were opened fully" (diénoikhthésan hoi ophthalmoi). In light of the use of the APHANTOS + BECOME expression to refer to the sudden vanishings of gods, demons, and other spirit beings, the expression is probably quasi-docetic in Luke 24:31 by describing Jesus in a similar manner. The motif of his disciples not recognizing him is also consistent with the docetic view that the Redeemer took on various guises (cf. "How many likenesses did Christ take on because of you" in the Nag Hammadi Teaching of Silvanius; Clement of Alexandria, Exc. ex Theod. 74.2, Ascension of Isaiah 10:7-12, Epistula Apostolorum (E), 13). The comparison with Acts 8:39 is not valid because there APHANTOS + BECOME does not occur in this verse; Philip is instead described as hérpasen "snatched, raptured" by the pneuma kuriou "Spirit of the Lord". This is a very different concept -- one of physical removal. As for the use of aphantos and the text in Luke 24:31, Origen attests their popularity among docetic gnostics (Contra Celsum 2.62, 2.69).
The meal setting in this text is also not one that asserts the corporeality of Jesus. He "took bread, broke it, and gave it" to his disciples, but he did not consume it. The passage in v. 37-43 however is quite different in being anti-docetic. First of all, it construes the docetic view as a misapprehension on the part of the disciples: "They were startled and frightened, thinking they saw a spirit (pneuma)" (v. 37). Then Jesus directly refutes the docetic view by asserting his corporeality: "Look at my hands and my feet. It is I myself! Touch me and see; a spirit does not have flesh and bones (sarka kai ostea), as you see I have" (v. 39). Then there is an additional assertion of Jesus' corporeality by having him eat "a piece of broiled fish" (v. 42-43), something that the prior narrative failed to relate. The anti-docetic nature of these stories are quite apparent; these verses are cited as anti-docetic prooftexts by orthodox apologists for centuries. More significantly, Ignatius of Antioch in the early second century related an independent form of the story related in Luke 24:37-39 (most likely drawing on it in oral form) as proof against docetism:
"For I know and believe that he was in the flesh (en sarki) even after the resurrection, and when he came to Peter and those with him, he said to them: 'Take hold of me, handle me and see that I am not a disembodied demon (daimonion asómaton).' And immediately they touched him and believed, being closely united with his flesh and blood (té sarki autou kai to haimati)" (Ignatius, Smyrnaeans 3:1-2).
This is direct evidence that such stories were told to refute docetic claims about the incorporeality of the risen Christ. The profound conceptual contrast between the Emmaus story culminating in v. 31 and the subsequent epiphany in v. 37-43 constitues a seam which in form critical analysis may indicate the transition between distinct traditional or literary blocks. Moffatt (p. 275) moreover notes that the Emmaus story makes an ill fit with both 24:1-11 and 24:36-43 in its present context. The Emmaus story assumes that Jesus had already appeared to Peter in an epiphany distinct from the Emmaus episode (v. 34), and yet v. 12 makes the point that Peter had not seen Jesus and "wondered to himself what had happened". This is another indication of a seam, as the Emmaus story evidently came from a circle of appearance stories where Jesus did appear to Peter (John 21 belongs to this tradition). Another is the fact that Peter is called "Simon" in the Emmaus story and "Peter" in v. 12. It should not be forgotten that v. 12 is itself possibly an interpolation (cf. textual attestion, Johannine vocabulary, its awkwardness), but this does not ease the ill fit of v. 34 which refers to an event otherwise not narrated in the text. As for the connection with the subsequent passage, Moffatt notes that the agitation and "doubt" (dialogismoi) in v. 37-38 makes an awkward fit with v. 34 where Jesus' resurrection was already confessed as "real" (ontós) from his earlier apperances. Moffatt also notes the Lukan style of 24:36-43 (compare the attention on physical form in Luke 3:22, sómatikó eidei "bodily shape"), regarding this as a Lukan composition, while treating the Emmaus story as possibly "taken from a special source". That the story circulated independently is possibly indicated by its attestation in Pseudo-Mark (Presbyter Aristion?) 16:12-13. Finally, the questionable textual authority for "Johannine-like" v. 36b (cf. John 20:19, 26) and v. 40 (cf. John 20:20), where the verses are missing in certain text families, is similar to that of v. 12 and strongly suggests that John 20 was further used by later redactors of Luke 24 to stress the corporeality of the risen Jesus. I think there are other data that bear on this question but I would need to do further research to check the sources.
With regard to your other comments...
Even the (controversial) Gospel of Peter teaches a bodily resurrection (see verses following the phrase "And when he had said it he was taken up"). Thus the Gospel of Peter is obviously not teaching some sort of early spirit resurrection only doctrine.
Again, I need to refer you to the christology of Cerinthus and other early docetists. The human Jesus was the fleshly "vessel" which was filled with the heavenly Christ who came upon him (cf. "entered into him," Gospel of the Ebionites 4; Epiphanius, Panarion 30.13.7f) during the Baptism, and who left him while Jesus lay dying on the cross. Most scholars believe that the Gospel of Peter has a similar christology. This is why the Gospel of Peter 5:19 has Jesus say: "My power (dunamou), my power, why have you forsaken me," this is supposed to be a reference to the heavenly Christ leaving Jesus' body. Then immediately after this, the verse says that "he was taken up," and as I already showed, this is exactly the language of heavenly ascensions in the literature. The "bodily resurrection" that is related later on is that of Jesus who had been buried in the tomb, and he is accompanied by the one who had gone to preach to the dead (in the form of a talking "cross").