I have not worked with an air suspension system while setting up a hitch but my first thought would be the air system would have to be turned off while setting up the hitch.
Filter the information you will get here looking only to those who have set up such a system because conflicts between the hitch and suspension are to be expected.
I would also consider going to a Cat scale before and after set up
WBCCI 12156 AIR 3144 WACHUNG TAC NJ6
2004 Excursion 4x4
1991 34 ft. Excella +220,000 miles, new laminated flooring, new upholstery, new 3200 lbs axles