A question and then a hint from someone who knows a lot more than I do of these things.
Would there be any problem in transporting wet prints in a zip-top plastic bag?
Now the hint: A very experienced photographer and printer (Jim Dow) suggested clamping two squeegeed prints together, back to back, and hanging the pair to let them dry. He uses a clamp at each corner and says that they dry nice and flat. This is the way he did all of Walker Evan's images for a show at MOMA back in the 70's. The clamp marks are supposedly the only way that museums and galleries can now tell his printing from that of Walker himself, for whom Jim served as darkroom man for some years before the show.