Soap and water don't cost much. many/most campgrounds won't allow us to wash our rigs our selves. They get a kickback from the outfits they let in to wash at 125.00 and ore per pop.
We washed ours in Little Rock this last trip in the cool of the evening. Took maybe a n hour total.
I couldn't reach the top above awnings. I'm not supposed to be on ladders.
Washed the car, at the same time.
She rinsed I sudsed, Rinsing brush between loading the brush with soap.
I don't do it much any more and am ebarrased some times by everyone that take the pride in their rig, of having it sparkling at every get together.
If you have a horse you keep him in good shape. If you have a car, you keep it clean. If you are younger or better fit you keep your rig clean.
It will always get dirty again so.....
I have in the past, in better shape, helped some, of the older Folks, then, wash their rigs.
Doesn't matter how old the rig is a bit of soap and some polish will keep it looking new.