We bought the best Adco cover for our fifth wheel. Only used it in off season.
Padded the corners, on top.
Strapped it up snug but every time it got a little warm it stretched and had to snug again and again. We're talking winter and early spring.
We developed green stuff on the corners.
The winds would make it billow out and stretch again. Finally it tore during second season.
Neighbors bought one more recently. The heat build up caused problems with sagging plastics and wall covering in their fifth wheel. They kept it on when not using all the year.
The material needs to be more uv resistant and the seams stronger. A definate need for some provision of ar movement under the cover up onto the rv and perhaps two parts with a zipper or something instead of one piece and the door opening. That would mean more costs. It is really not as suitable for what most RVers need as would be a permanent shed.