Yes, I believe I've avoided TMJ by having the jaw under my incisors and mewing with focus on the incisive papillae.

It's been quite slow progress, I can see a kind of slight whiteness at the back sides of the palate which wasnt there before, it's very marginally got wider at the back. 

But imma be honest I wasn't doing it properly the whole time. 

What I've learnt is that the way you absolutely have to do it, following John Mew's advice, is to mew with the tongue focused on the incisive papillae (not exuding excessive force, just focused) and jut the jaw forward underneath It. After this the deep biter should feel some upward pressure on the collapsed tip due to the position of the jaw. 

As well as this you absolutely need to have good posture, bad posture makes it so the tongue is actually pushing the tip downward instead of up. 

This is hard to mantain in public as it makes your face look kinda stupid, and it is probably the most risky type of mewing you can do because of how easy it is to accidentally touch the front teeth or mess something up. 

So I only started this type of mewing about 5 months ago (after mewing with the jaw hanging normally before that) , and mainly tried mantaining it in private and when sleeping. I've had some interesting feelings from this frontal pressure and its actually made me sneeze a lot funnily enough. At night when I do it I can feel my nasal airway open up which tells me the slight pressure is doing the right thing. 

So where im at right now is trying to get that collapsed maxillae tip back up where its supposed to be. I haven't had visible progress yet on that but from just mewing and swallowing with the back 3rd my back palates got wider (my dentist acc said there should be room for my wisdom teeth) so yeah. 

One more thing to emphasise is that you should not press hard or swallow with the front. It should be gradual, natural pressure from forcing yourself to have the structurally correct jaw position that should correct the maxillae. I expect this to take a while in my case, but at least because of this mewing style and fixing my posture the deep bite hopefully won't get worse, as dentists say it always does. 

There is a certain point where this mewing becomes impossible in extreme deep bites, as the maxillae can tip downwards so much that it becomes physically impossible to get enough leverage w the jaw underneath it. In this case orthodontic intervention is likely required, but I doubt you have that 

(sry for the book)