I highly recommend the longer wheelbase for its marginal extra costs. I also recommend the 3/4 ton for its standard RV towing equipment. However, you should be under all the ratings with that TV. Check the tire and loading sticker for as equipped payload. Mine says 2051.
I recommend loading as much into the TT as possible, not the back of the TV. Then only 10-15% of the weight goes onto the truck's axles.
5.3L/3.42/6-spd will know your socks off comapred to your current TB. That's like your truck with 4.56 axle. Use tow/haul mode, and M5 to lock out 6th gear.