2303lb payload less (4ofUs with gear and other******in cab guestimate of 853 lbs less guestimate WD hitch 100lb) = 1350 left for trailer tongue weight.
1350lb tongue weight (and assuming it will be a max of 15% trailer weight) = 1350lb * 100/15 = 9000lb max trailer weight.
Replace guestimates/assumptions with your own measured values for accurate numbers, but this should be in the ballpark. Personally with the gasser, as others have mentioned I would limit to well below 9000 lbs as well (speaking from experience having towed with gas and diesel).
