We have the paint checking you describe in the dark color paint on our 16 yr old rig. It just began showing about 2 years ago.
I understand the fix to be redoing the fiberglass under the paint. Very expensive. I believe The Paint Department in Chino, Ca has some expertise in this type of repair.
This seems to be a more frequent occurance on the newer vintage coaches where darker paints were used and the fiberglass problem surfaced.
Our experience is that so far it is no big deal, and certainly not a repair to accomplish for cost vs benefit. Our checking is not visible from 10' away.
More info here Country Coach full-body paint
However, if you do not own this coach yet, you may want to get repair estimates before doing the final transaction.