I bought a $60 factory remanufactured, extremely small (like toaster sized) pressure washer at Big Lots ($90 new/regular at Northern Tool) and using a micro fiber pad on a stick (WalMart Rubbermaid for $8) can wash a 45 footer using the inverter to power the pressure washer and only 15 gallons of water from the RV water tank and viola, one sparkling clean 45foot rig....

The idea of the pressure washer is to minimize water use during rinse and these baby models are so low pressure they can't hurt anything - Not even the Diamond Shield. They are easy to store and use little electricity meaning they can be inverter powered.

I quickly wet an area (like a third of a side) using the pressure washer, dip the pad (a non full paint rig can use a brush instead of the micro fiber pad) in a bucket of soapy water, scrub the area, and then rinse with the pressure washer. Usually only 15 gallons total and about 30 minutes time for a 45 footer.

Nothing like doing a wash at a pull out on a high mountain pass overlooking a beautiful scene. Takes the drudgery out of washing your rig!

If you use a commercial wash, I'd suggest ONLY Blue Beacon as they have an RV specific process (which also includes NO acid based soap) and know what Diamond Shield is and to back off the pressure wands when cleaning those areas. They really are not all that expensive for what you get, about $50 for a 45footer.

But, like I said, I do mine using the above tools on beautiful pull outs and enjoy the view while washing....