These covers may be nice when they are brand new but must get awefull dirty after one winter. Can't imagine washing one of them. Pool covers were hard enough to clean after one use. Then you have to store it and hope it does not rot.
I'd rather wash the coach in the spring. 6 year old 5th wheel still looked like new with just an annual wax and that was with a PITA rubber roof.
Sure my FG roof will stand up much better.