You need a truck wash? Get ye to a Meijer's store and pick up a decent pressure washer .. Now here you have two choices.
First, You can tap off hot water either off the water heater drain in your house or the laundry faucet if you wish hot water.. Or just use cold.
Wash it where it's parked.
Then drain the hose, Drain the pressure washer, and bring 'em into heated storage for the rest of the winter (Basement of house or "Junk room").
It is what I would do/did. You should see at least one more warm day before the end of Jan. (normally do) but do not count on it.