I see no problem with using mylar on the back of backglasses to arrest peeling or flaking, I do it all the time.
It's easy to apply, and it works. Used to use triple thick but the stuff is messy and unpredictable. Mylar is way easier to work with and more effective. Of course, you only get one shot, so don't get too greedy. I just cut small pieces and use where I need to.