Seems to me that if a ban on vehicles over such and such length was put in place, then the shortest distance a truck driver could legally take could not be over deals gap. Thus, trucker would get the miles for going around the road that is obviously unsuitable for such a vehicle.
I figure a good way to go about it would be for the two states to agree to restrict traffic with trailers over a certain length and traffic without trailers over a certain length from using the road.
great point. if there is a law in place, you're employer would be forced to pay you for the NEXT shortest distance.