We cover the RV. Sun and UV damage will hurt your RV faster than anything else in storage. Paint can be waxed, but a rubber roof, plastic bits, and the seals on every opening, vent and such are exposed too...
And, don't forget to cover the tires too. The outer sidewalls of our last set of tires had the only visible damage...all interior tire surfaces looked great.
Covered storage is best...of course.
And, covering the RV IS extra work...but for us (keeping the RV longer than others - maybe) it is a no-brainer to protect our investment.
Don't cover the RV when it is dirty from a trip. Wash the RV to keep the inside of the cover clean and to save the cover to RV body contact from wear marks.
On removal we fold the cover on the roof like big burrito...makes install easier and being folded, storage it much better..