There was salt under the pickup -- and even using the garden sprinkler it took quite a while. The sprinkler would get the salt off from one side of the frame rail(for instance, but then I'd have to move it to the other side. In other words, back and forth the length of the pickup, back and forth across the width, too.
As for the trailer, which got a double bath (in as we arrived, then out to the bend in the road for Salt talks, then back in, then out to go home) - I did a complete brake inspection when we got home and was amazed that things were pretty clean in there. All brakes worked, all wires still looked like copper, not green toothpaste, and so on.
With that little mention -- I'll be selling the trailer this spring and getting a new, bigger one. If you're interested let me know -- I'll put photos and an ad in the "for sale" section soon.