*clay bar (Meguairs and mothers make OTC clay bars, and other internet available brand like Pinnacle and and Chemical Guys)
*polish with orbital buffer, correct pads and fiberglass safe polish
*use fiberglass safe compound on rough spots then go back over again with polish
*LSP (last step protection) this will be a high grade wax or sealant
your choice of polish and compound should be fiberglass specific or fiberglass safe products.
almost all waxes and sealants should be compatible with your 5th wheel.
Meguiars makes RV/Boat specific products
as for a orbital buffer, Porter Cable makes a great entry level (still pricey and not HF junk) product that works great and eliminates potential surface marring or burning that can happen with rotary buffers
also, pad choice is critical. again, the auto detailing forums are a great resource, and they will be having their black friday sales soon!!!
I just used Meguiar's clay bar on my truck. It did an amazing job removing all of the crud I could not scrub off. (requires a lot of elbow grease) It feels incredibly smooth now. Definitely worth trying.