I use Whitey's (Jim's) method all the time for all sizes of fiber prints. I use a hanging line, back to back, top 2 corners from the line, bottom two with clothespins (the plastic kind). They come out as flat as they can, edges buckled somewhat depending on humidity at the time and rate of drying (these two are interdependent). The dryer the room, the more edge buckle. You can read a lot about flattening prints in the second sticky of this forum.
But as to the OP question - either do a complete wash before or after getting home, but I would transport the prints just like Thomas says.