You could have truck drivers just at the start and end points of a route. Trucking companies can have representatives at the border, who then guide it through customs. No need to sit in the vehicle for hours.
Again, it isn't the physical act of driving that matters. It's that the truck driver is vetting the cargo. He is responsible for the contents, he is going to jail if there is something illegal in his truck. Someone jumping in the cab just shy of the boarder isn't going to be of much use to a boarder guard asking questions.