Hey Rebel,
They don't get it do they? You may have to send multiple letters, say one a week or so for awhile? I like the letter you supplied in the link but you could send the cease & desist one at the link below but the address for the wt needs updating. I do know if you send it to NY it will eventually reach back to the elders in your area. Worked for me anyway.
https://www.jehovahs-witness.com/topic/153587/cease-desist-letter
Though I was making a stink with my jw so that probably helped. I also threatened to show up at the kh during a meeting with some paid muscle to protect me, go to the front with a blow up picture of our house and address and tell the whole damn cong that this house was a no call and then leave. Yep, that seemed to help too.
They are not the brightest bulb so it takes a bit for them to understand you don't want them on your property or their trash.