9100-9300 is with the truck completely empty. Once you max your payload it drops what you can pull trailer wise. The combined tow rating is 15,000lbs. If you max your payload the truck is around 7,000lbs which leaves 8,000 max on the trailer. Even then most people don’t recommend going much over about 80% of the max combined. I would say a 7,000 pound trailer is the max you would want to pull with a Trail Boss.