We are on the road all the time, we have no residence. Most RV parks will not let you wash your RV. I have used truck stops that charge from 75 to 125 dollars and do a terrible job. What do most do?
A lot of areas have a "coin-op" truck wash, RVs fit very nicely. There is one about 20 miles from the house, and I spotted (and used) one in Drumheller Alberta (after some rain, and red-dirt roads)