Hi,
  My brother spent a lot of years in trucking - first as a driver and then as a dispatcher.
Smallish company with all flat bed trailers.  Once, while he was still driving he had a
container of hides as a priority haul from Portland to Vancouver, B.C. (had been delayed
a couple of weeks in the summer).  He got to the U.S.-Canada Border and the border
guy said "I have to check the load".  My brother had some idea of what would happen
so he got up and unsealed it and hopped down and said - go ahead and check.  The
border inspector hopped up and popped the doors open (center opening) and a 
bluish green "fog" came pouring out of the truck and flowed all over the parking area
where they did inspections.  He was able to avoid actually getting in the fog (border
guy did not) and they told him they couldn't inspect until the fog was gone ... and so
he had to park it way off to the side (as directed) and it sat for several hours before
they risked even going back to it long enough to peek inside.
  If you ever want to smuggle something across a border - putting it inside/under a
hide load would be a good method.  *G*
                                                                                       - Jim in the PNW