Here's the least expensive way to get your RV's roof - as well as partially the sides - protected from the sun ... which is the most important protection for an RV to insure that the sun's heat and UV rays don't ruin sealants and plastic items. (Of course this approach may not work if you live where you get heavy snow loads):
http://carportsandmore.com/canopies.htmlWe've used one of these inexpensive carports for years to protect our 2002 family sedan. It's exterior is still in pristine condition being protected this easy way. I sunk concrete footings into the ground and bolted the carport's posts to the concrete to keep the carport in place during heavy winds.