You might try the Red Max Pro #3 route instead of wax. This thread tells it all. Red Max Pro #3 Question
It takes prep time to remove old wax, grime, and chalk from fiberglass, but then application is MUCH easier and faster than wax!
Prep: Use TSP (trisodium phospate) and Barkeeper's Friend to clean off RV. Rinse.
Then apply 4 coats of Red Max Pro #3 floor acrylic (available at Lowes or Home Depot) If you can't find RMP #3, Zep has High Traffic Floor Finish is the same product, different label. It works on fiberglass, paint, vinyl graphics, window trim, etc. Gives a high gloss protective finish that only needs a refresher coat once a year.