Good material, Saint.
Number crunching JW membership is a formidable task. There are so many factors to consider and conflicting numbers to deal with. It is difficult to sort othrough the estimates, the sources of data, etc.
Your theories are reasonably sound, at least, based on the information that is available. There is one thing though, that might need consideration. You speak of the Bible Students/JW men who signed the declaration, or simply went inactive, as being conscripted, and then returning after the war. I think it is reasonable to assume that not many returned. A large number would have died as war casualties.
I still, however, hard a hard time reconciling the numbers of JWs with the numbers of the Bible Students. The WTS always claims all the Bible Student numbers as their own, when there is much historical documentation that many German Bible Students did not consider themselves part of the WTS in the years leading up to WW2 and during the war. The numbers that the WTS claim as their own are padded with many Bible Students who did not follow the Rutherford/JW doctrine and who had already left to form groups such as "Free Bible Students Association". Those Bible Students who had broke away from the WTS would also have worn the purple triangle in the camps but they would not have considered themselves Jehovah's witnesses or part of the WTS.