I had a similar situation a few years ago when we had a drought.
State law allowed no car washing, and at the time I lived along a main road, sure to be busted if I broke out a garden hose and wash bucket.
The loophole in the law was that commercial car washes could stay open, and in Allentown we have a place that does a hand wash and dry for $6.
What I did was had them wash it, then drove a few blocks to a shady side street, and sprayed the car with Meguiar's Quick Detailer.
Not ideal, but better than nothing.
If you really want to run your orbital, have you considered a power inverter or small generator?
I can imagine you are always on the lookout for a source of "free" power ... and water, and shade....

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Bob Roe
Lehigh Valley PA USA
1973 Olds 88, 1972 MB 280SE, 1978 Datsun 280Z, 1971 Ford T-Bird, 1972 Olds 88, 1983 Nissan Sentra, 1985 Sentra, 1973 230.6, 1990 Acura Integra, 1991 Volvo 940GLE wagon, 1983 300SD, 1984 300SD, 1995 Subaru Legacy L wagon, 2002 Mountaineer, 1991 300TE wagon, 2008 Murano, 2007 R320CDI 4Matic 52K, some Hyundai, 2008 BMW 535xi wagon, all gone... currently
2007 Honda Odyssey Touring, 2014 E350 4matic