We store ours in a storage yard. I have a five gallon pail & squeegee with the foam scrubber on the opposite side. Put it on a expandable painter pole to reach the top.
I fill the pail at the storage yard with about 4 gallons of water and a very small amount of cider vinegar ( maybe a teaspoon, helps not to leave streaks). That's it. Dip the squeegee in the water scrub a wide area and then turn the thing around and squeegee it off ( get it off before it dries). I always have just over a gallon in the bucket when I finish. Enough to do the wheels with rags. Saves on water and the MH looks great.
Every spring I pay the dealer to scrub the roof and treat it. Here is a waterless cleaner on the market.
http://washwax.com