I can tell you how I have "done it on the road"...However, you will need to bring some supplies. There is no safe way to wash a car without using some detailing supplies, so if you have zero room - just wash it when you get home. Better to do that, leave it dirty, than to take it to some Swirl-O-Rama-Wash-O-Matic.
First thing, just pressure washing the car off as "good enough" is no good. Your car is dark (black?) and your in Florida I believe - this will likely lead to horrendous water spots and etchings. Just ask anyone down there whose black car got blasted by a sprinkler and dried in the sun.
The way I did it in FL is I brought a few supplies:
-32oz bottle of wheel cleaner
- Daytona mini wheel brush
- Montana Boats Hair small wheel brush
- 2 collapsible buckets. These are great in a pinch... I got mine for $10 on EBay:
They fold up virtually flat and take up little room.
- a 22oz bottle of UWW+ concentrate
- some towels
- a sample bottle of tire dressing.
.... And that is pretty much all you need. You can hit the Pay-N-Spray EARLY in the morning (like 6:00). Nobody is there and it's cooler out - you can work in the bay and nobody will bother you at that hour (shelter).
Use their water supply to clean the wheels conventionally and fill your folding wheel bucket. Pick a wheel cleaner that works decently on tires as well. Then, pressure wash all the sand and dirt off the car and do a waterless or rinseless (GDWM) wash there (car is still wet in bay). Dry as you go along.
That's it - pretty easy. Worse part about it is you will have to lug around wet and dirty towels. Bring some plastic bags to put them in. I always use DI water to waterless/rinseless wash. You can pick that up anywhere while you are there.
When you are done, dress the tires. On the road I'll just use blue paper shop towels as applicators folded up in 16s. Then when you are done, just throw it out. One less thing you have to carry dirty back with you. Or, you could just bring a few pieces of grout sponge and toss them out as you use them.
