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?
I use a bucket and do a small section at a time.I don't use a hose to wash and rinse. I have never had an issue. It does not get the best job but certainly gets the worst part. Having someone wash it can be very expensive as mentioned.
Waterless wash products. Spray on, wipe off. Most of the dirt on rigs is dust anyway, not hard, scratchy dirt. Most campgrounds don't want the water used, or the mess, neither of which comes with a waterless wash. I know some people with rigs that are 7 years old, they've never seen soap and water.... and look great.