Salt wrecks vehicles. Period.
Yes the salt can and will eventually rust out everything. Frames, springs, body, wiring. You name it.
Post up a couple picture of the trucks snd areas you’re concerned about.
We spray vehicles up here with oil, every has their favourite oils or rust inhibitors. Big shops here do it in less than an hour, the get under it, pressure wash it, and spray it with big spray guns. Personally, I wash my trucks out my self, let it dry out several days, and then spray it down - every thing and everywhere, inside and out, top to bottom, with a couple of differnt rust inhibitors every year.