If I were you, I would look into a shift improver kit. With the towing you do, a high stall converter is going to build a lot of heat and will need a GOOD cooling system to keep temperatures down.
Your also looking at a lot of work! I'd rather pull 2 engines than have to pull a tranny with the transfer case. The transfer weighs a ton and in my opinion, is a pain in the butt.
Unless you have the money to get someone else to do the work (which is the easiest way).