We wash our High Wall Pop Up after every camp out. due to the pollen dust, lime rock roads that are so dusty here in fla and reg road dirt.
We use RV Wash and Wax that we purchased from Walmart.
It works pretty good. and always wash in the driveway. after washing we towel dry it so we dont get any water marks from the sun . we also make sure the roof is dry.., then we cover it till our next camping trip..we love the cover cause without it we would be cleaning it ALOT more then we do now...
Good luck with whatever you decide to use. anything is better then nothing.
tc/kc