Wow! That's an interesting problem. I don't have the problem but I will be very interested in the answer. Fifteen years ago, I could have answered your question. Technology, most likely, has changed in that time. I am not at all up to date on this subject.
Just for the heck of it, here's the answer from 1992. At that time, a complete recoat would have been the solution, if a solution was wanted. With 60% damaged, it would have less expensive to redo it all, than to "spot" it. Worse, it would all have to be sanded down to feather the edges where the clear-coat was missing, which would have damaged the color coats, as well. Therefore, the solution would have required a complete recoating, including the color coats!
I would be scared to death to estimate the cost today, and I have no idea at all. Back then, the cost would have exceeded the value of a 15 year old coach, by a multiple. I would guess two or three times the value of the coach, back then.
That was then. This is now. Powerjen, like you, I await the advice of those who know.