Try a product called Gel-Gloss. I have used it for the 99' Coleman and our 05' Aerolite hybrid. It is great on fiberglass surfaces. It's both a cleaner and a wax. It comes in regular and heavy duty. Most RV dealers sell it, plus Camping World. Here is a link Gel Gloss
. If you have a lot of oxidation I would go with the heavy duty.