Sliding tandems

Our company has fixed fifth wheels and on the New Volvo's were always over weight anywhere from 500lbs to 1200lbs. The frame has 4 holes to move the fifth wheel back to move weight off the steer tires. Even though the company is reluctant to move it for the driver. This forces us to keep our fuel tanks no more than 1/2 at all times and we need to get permission to run at anything over 40000lbs per load. So whats the deal? I used to have a sliding fifth wheel and traveled thru 48 states. Never a problem, they act like I don't know what im doing and all im asking is to move the Fifth wheel toward the rear to alleviate the over weight on the steers and then I can move the rear tandems to balance the load. They keep citing the Bridge law and say they are not going to move it so we can haul the water and paper loads. Two Fifth wheel holes should work at 500lbs but they are reluctant to do so? What to do? Any help resolving this issue?