There is one other option.
Some of the pressure washers will work out of a bucket if you set them up correctly.
This is assuming you have a power source though.
(Although there are battery pressure washers too)
I have used this method successfully during water shortages.
If you are frugal you can wash a car on one large bucket.
For you though you will need to use approx 4 - 6 of them i would guess.
