help me build my tow rig

so i bought this 02 350 last year and i havent been happy with its power. i tow a 12k lbs toy hauler and about 1 to 2k lbs on my truck. going up the grade on the 15, it kill it. i go like 40 mph. i thought i needed a bigger truck until i talked to jody at dptuner. he is getting me an adjustable chip to add 80hp and lower settings for altitude. the truck already has axhaust. i am not sure which kind. and it has some sort of intake. it has the additional pipes that go into the fenders that stockers dont have. it also has 35's on it.

i know i need to get back to stock gearing. right now it takes a 2" raised hitch to hitch up to my trailer. if i put 33's on it, the tires will look a litter smaller, and my hitch will be another inch lower. so should i go with 33's or should i just do a gear swap to 4.10's or 4.30's?. if i go with 33's i will have to get new rims and tires, cuz my rims now are 18's and there arent too many good option for 33's with 18" rims.

other than that, what other things should i do to make this a good tow rig? i bought some guages. a turbo guage and pyrometer. should i get other gauges too?

please help me revive this truck and make it work for my application.