On my 05 Monaco, I first noticed the front cap blistering above the running lights. I bought matching automotive paint, sanded and re-sprayed the area which left a line that wasn't bad. I did the same on the rear. Finally, the sides started to go. I took it to an RV body shop and they painted both caps and both sides all one color. They did this buy using the dark brown paint on my front cap and carrying it all the way back, painting over a couple of areas, above the drip rail that had other colors. They made a paint line just above my rear running lights where the dark brown created a new line on my tan paint at the rear. They gave a lifetime guarantee.
If you let the issue go too long, you'll start to get large cracks (the size of the edge of a business card) that are not repairable by sanding. I had a couple and the had to take the paint down to the fiberglass, use an epoxy premier and then spray. Mine cost $3000.00. My neighbor had his sprayed in the front yard by a mobile guy for $1200.00, but over sprayed the coach. I know several people who have had mobile guys and professional shops do the work. To me, paying the shop to do it is worth the money.
Don & Mary
2019 Newmar Dutch Star 4018 - All Electric
2019 Ford Raptor Crew Cab