We've got twin trucks... Pearl LX470 w/ Gamiviti racks. Nice.
The car wash you drove through forced all the salt deeper into the nooks and crannies of your undercarriage, and the treatments you applied will trap it in there forever. Also, the fluid film will attract dirt and help it turn into sort of an abrasive sludge, causing a bit of extra wear every place something moves.
I live in central NYS, right in the heart of the snow/salt belt. Folks make a mint in this area selling every kind of rust-preventative measure they can think of. Pretty much nothing really works. I try not to drive the cars I care a lot about in salt constantly, but sometimes you just have to. They're just vehicles. Beautiful, wonderful vehicles... but just vehicles. I get way more enjoyment out of driving my LX than I do looking at it, and it's an absolutely phenomenal winter vehicle. My wife's ML500, already well down the rusty road, is our go-to in the winter, but every time I take out the LX I want to KEEP driving it in the winter. Might as well enjoy one of the things it excels at. Enjoy its capabilities to the fullest, or look at it? Me, I'd rather enjoy it and not worry.