Are you able to cover your RV?  (pardon the sarcasaam here), but I assume only you can answer that.  Now SHOULD you cover your RV? With a tarp?  Well tarps certainly do cover them well. Tarps are generally more light weight, easier to handle, IMO they repel water BETTER than an actual RV/auto type cover.  However tarps are also more rigid (not as soft on the paint job). Tarps can cause the scratches and even paint wear due to their stiffness (rigidity). Tarps are sometimes harder to fasten down (because they are a universal piece). Tarps may repel water better, but they also do not breathe, which allows the moisture that forms (naturally) between the top skin and the tarp to not dry out very fast. This can cause premature rotting in the roof and eventually the sidewall structures.

Now comes the question (Would I cover my PUP with a tarp)?  Yes --- but I would place something on the roof first (like a 6X6 piece of wood in several places) so the tarp does not fit tight against the roof. This would allow the roof to be covered, and at the same time give breathing room for the moisture to dry.

The lean to or carport type support is a better idea than directly on the camper. The last thing you want is to trap moisture or build up heat on the roof.

Make sure its a breathable tarp. If its not moisture problems will happen. Why cover it? Rv sales yards dont.

Seams can leak at anytime as well as the A/C seal.