For previous posts on this popular subject search this Forum for `rv cover'. I think most RVers think of the covers that envelope the entire outer surface of the RV. The pictures look nice but I can't imagine how difficult it must be to install it, remove it and store it.
We use a Sunshield tarp that covers the entire roof and overlaps part of the sides, front and back depending on the size of the tarp that is used.
We hold it down with ropes connected to old boat fenders half filled with sand. The sand provides weight and the vinyl material does not scratch. The ropes are long enough so that the fenders (some call them bumpers) hand down below the gelcoat surface.
Removing it is easy. Just disconnect the fenders and pull it down. We stretch it out on the lawn and fold it up like the sailors do the mainsail, accordian style and bundle it.
Putting it on requires me to get on the roof, pull the bundled tarp up via a rope and unfold the accordian bundle front to back. It takes about 15 minutes.
In the winter we put the black side up to absorb heat and in the summer put the silver side up to reflect heat.
Not sure how many more years my Wife will allow me to climb on the roof (age 77) but it works for now.