I have a 2004 Dodge 3500 DRW 4X4. My 11.5 foot Bigfoot weighs 4000 lbs. I flat tow a 3000 lb (modified) Samurai 4x4. I tow with a 2"x2"x1/4" square tube about 46" long. I do use side chains on the extension.
I bought my truck with the Stableloads installed by the previous owner. The Stableloads only make the overload springs engage about two inches sooner. They reduce the rear truck squat by about 3 inches.
I installed an anti sway bar. I was not uncomfortable without it, but it did reduce some sway. The wife says it really raised her comfort level.
I also installed airbags. The airbags were not needed to carry the TC, but when and if I tow a trailer they may be useful. You can change the ride smoothness and lift the rear of the truck to its stock height. I haven't measured, but I think I can raise the rear higher than stock.
My truck OEM tires 235/80R17 load range E (2835 lb as a dual). That is 11340 lb for the rear axle. The door decal says 9350 GWAR for rear axle. My truck rear axle, with the 4000 TC, is 7240 lb.
This "With the Dual does that give me 2635 x 4 = 10,540 load? My RR GAWR is 8200. Thanks for all your help here." is correct.
I would be comfortable with your truck as it is. I would run it and make improvements to suit my preferences.
