"To cover, or not to cover: that is the question..."
There's no doubt that a cover can keep the elements from getting to your finish...
... But so can a good coat of wax!
Every RV store and dealership is always more than happy to sell you one; but they don't use them on their rigs.
When we first bought our Outlaw in 2017: the salesman pushed us toward the covers, but service guy came out of the back, and saw what we were looking at. He came over and said that wax will protect the rig almost as well as the cover; but without the risk of flapping material actually damaging the surface it was meant to protect.
They have to be secured so that NOTHING flaps, and all of the edges have a barrier between them, and the rig...
But it si your RV, and your choice to make...