Two things. First, ZEP or RMP in relation to UV is completely irrelevant. These products are transparent, which means they are neither harmed by UV, not do they protect the surface underneath from UV. The reason it peeled is because of what the OP posted - Heat. Don't over complicate the processes.
Secondly for the OP. When you strip ZEP or RMP, it leaves and ugly edge where the transition goes from coating to stripped area. This edge will not buff out. If I were you, I would mask off right at the edge to the color or stripe transition and only apply stripper to the bad areas. If this works, and the transition edge is OK, consider yours self lucky and you can choose what you want to do next - re-apply or leave it. If the transition leaves and edge that looks bad, then you are stuck stripping the whole coach, or at very least, stripping to a better transition area. That is pretty much about the only thing you can do.
For myself, I have only put 2 coats on my coach and live in the north, so I am hoping I will not have flaking problems, or if it does flake, that it will not be as hard to strip.