"Makes it tough, though, when a couple of the jerks won't shut off the grain cart or combine unload spout, when you wave "enough". Most will stop, but there's always a jerk or 2 in the crowd. After a short discussion, we come to terms." 

Not really hard to have that discussion if you are custom hauling,  just tell them you are over loaded and open the traps and let it out on the ground til you are legal.  Now if it is your own crew.......  that doesn't work as well.

I don't have trucks but ship off farm and most of those trucks can be as close to legal as they want by looking at their air gauges.