Whats your payload for the truck? Don't see that number.
Weighing your config, loaded ready to camp, is the right answer. Short of that, start with Payload for the truck. Subtract what you have in the truck (passengers, cargo etc). Remaining cargo capacity is what you have available for tongue weight and the WD hitch weight.
The fact you burned up the torque converter shows you were not a good match. The fact you upgraded that component, to include the tranny cooler is great, but that does nothing for payload/cargo capacity.
Cargo Capacity can be found on the door jamb on the yellow sticker.
Mike