I've wondered if it would be worthwhile taking along one of the hand
pump, pressurized garden sprayers full of fresh water. You could give a
quick spray as soon as the trailer comes out of the water.... should
help until a proper hosing can be done.

This sounds like an interesting idea. We should get one with a metal
tip (where the water comes out). The plastic one is no good. The
spray is not even if we use a plastic tip.

It tends to wet the surface (that it is designed for), but not wash
away stuff from the surface. In order to wash away stuff, we need to
spray the same area long enough. This is still probably better than
not doing anything at all.

Jay Chan