The other option is to use one of the washing services that will come to an RV park, but they charge from $150 to $250 per wash, depending on whether they do any detailing. MUCH too expensive!
Finally, I found Blue Beacon Truck Washes, which are all over the country. They charge $28-$30 per wash for a vehicle the size of mine. They tend to be next to or behind big truck stops off major interstate highways. This one is at Exit 285 off of I-75 near Dade City, FL.
You pull around back and then wait in line with the big trucks. Usually it takes at least a half hour before you get in. There is ALWAYS a line! This one is from the Blue Beacon in Portland. They were washing out the inside of this truck. (That day, in the next bay they were also washing out a truck where the piggies had already gone to market--a really big stink!)
They were only washing the cab of this truck. A lot of truckers who own those nice shiny cabs keep them nice and shiny this way.
Now, it's my turn. You have to get out fast and go into the office to pay before the swarm of workers start washing your vehicle. This time I skipped the $13 clear coat wax. They will also polish your tires and do some other minor things for a few extra bucks. My vehicle was so dirty from the road, salt, and beach sand storms, a plain wash was enough.
They don't do any drying, but whatever they use really does an excellent job of getting off bugs and does not streak windows. In fact, after I hand wash it myself, I always have to do the windows, but they looks great right now, sitting in my campground the next day.
So, I have fallen in love with Blue Beacon! I don't have to wear myself out, get soaked, or try to find a campground (very hard to find) that will actually let me wash my own vehicle. The few coin-operated washes that my vehicle will fit into end up costing me about $20 in quarters anyway, so Blue Beacon is a real bargain and a true luxury!
There is also one in the southeast part of Florida, so I'll probably go there later in the winter for another wash.