A warning...if you consider using a pressure washer...
Do not spray/hit the window weather seals and/or the edge of dual pane windows...or the vent panels of any appliances... with the stream of the pressure washer.
All the items on the exterior of the typical RV are designed to carry rain water away. But a high pressure or continuous spray can cause problems from flooding to fogged windows.
A detailer did this to our RV.
And the same problem can happen if running an RV through a Truck Wash.
If washing the roof, start there. Because roof run-off will mess-up any clean side walls. If you have a "rubber roof", Murphy's Oil Soap is a good and gentle alternative to expensive specialty soaps or cleaners that will prematurely dry-out the roof.
Kim and Steve, Mustang LCDR (Ret), '07 Damon Outlaw #1193
I have seen gross intolerance shown in support of tolerance, Samuel Coleridge
WE LOVE OUR OUTLAW RV