Some RV parks allow a one time wash, most do not. Check their rules when you register. Consider using a commercial coin wash in addition to the truck washes. Most have an end bay with no roof, some even have a scaffold so you can get at the higher portions of the rig more comfortably.
Sold the Motorhome, joined the fully retired gang. '07 Winnebago Journey 34H, ISB-02, MH2500
Toad - '08 Ford Taurus X, Blue Ox, Aventa
US Gear UBS