Wash without drying???? RV

Hey guys its been a while. So I have a question. I just bought a 22 foot travel trailer. Its a 2016 but has that aluminum siding. Or at least i assume its aluminum. Either way it needs a bath. Im wondering though, is there a product i can put in my foam cannon on my pressure washer or just put in a bucket of water that i can wash and rinse but not dry that will not leave severe water spots? It will be washed at my folks house which has horrible well water and I cant put it under shade. I was hoping there was a truck stop car wash i could pull it through near by but unfortunately there is not. I mean honestly im not looking for show room detailing. Just trying to get the dirt and bugs off without making it look worse than before. TIA

My local detail shop rents those mobile spot free water setups. I've also seen various models for sale, pretty much for your exact application as they're marketed to the RV crowd. We carry spot free water because those mobile units are not really cost effective, but for your personal use I'd look into one of those for a couple hundred.

The cost of resin for well water will put a stop to that idea quickly.

Wash a side, rinse it with tap water, then do a final rinse with distilled water from a garden sprayer. Wouldn't be perfect but would be damned sight better then letting hard water dry on the surface.