Ditto on using truck wash for on the road service.
In CA they tend to be more expensive, but in other states it is a good value.
Than if you DIY, get one of those truck washing brushes and commercial painters pole ,that extends with click lock as those turnable locks become junk sooner than later.
Pulling my 40' conversion from storage and having garden hose at home took me about 20 minutes to wash it all. Not really detailed, but look good.
Than on the road I was able to wash front and end using 1/2 bucket of water.