You should have an automotive paint supply store in town. I have two near me. They sell all the equipment, paint and supplies for working on automotive paint. I have bought color matched paint as well as buffing supplies for my 5er front cap. Color matched paint was for another project, but they have 1000's of colors and can match anything.
Try a good size body shop that does cars, trucks, semis and RV's.
2017 F350 DRW XLT, CC, 4x4, 6.7 2018 Big Country 3560 SS "The best part of RVing and Snowmobiling is spending time with family and friends" "Catin' in the Winter"
Just a thought. If you have a sample of the paint or a true photo of the color, a hardware or big box store should be able to mix an exact color. The important thing is to get a paint for fiberglass and the correct "gloss". Just a thought. A marina might also be able to assist.
Are you sure it's painted? I think the caps on most 5th wheels are fiberglass. In any case, I'd probably call the dealer or a repair facility and ask someone. I had to chase down some tape for an interior wall panel junction and the dealer got me in touch with the right people at the factory and I got is pretty easy.