I often wash my trailer at campgrounds,when camping. Seems I never have time at home. But I do not drag out hoses, and bucket, and make a scene. I get a bucket of soap water and a sponge or a wash cloth and hand wash small sections at a time. I might do just the section from the front cap to the first window. Next day just the section where the window is. Next time the front cap, next time, the back end. Basically, it's wipe on - wipe off. No fan fair, and don't make attention. I don't worry about the roof. I do it a couple times a year at home.
Campgrounds may advertise "no washing RV's". What they don't want you to do is get the hoses out and run a thousand gallons of water. But the bucket and sponge works just fine. Never, ever have I been challenged by anyone for washing my camper this way. Also, when it comes time for waxing, I do it the same way, by hand, small sections at a time, and over several days.
This keep from getting too tired, and the camper is constantly getting washed down. It also does not take but a few minutes to wipe down a 3 or 4 foot section of the camper and then get about doing something else.
This is primarily how I do it. Been doing it this way for years now.