Ha, sounds like me about 10 years ago. Was taking the annual trip to lake of the ozarks and had no problem pulling the boat with my half ton. But at the time I was renting a bunch of equipment from Hertz and got them to rent me a new crew cab powerstroke for the trip......for $100! Cash
After that 2000mi round trip with a truck that didn't downshift except on big grades and the 12-13mpg vs the 8-9mpg out of the gasser, I promptly found a diesel and haven't been without one since.
Doesn't matter if I'm hauling the TC, towing my 32' sled trailer, boat or combo of both, truck always has the power and brakes to tow/haul with ease.
Take the diesel. Don't worry too much about the wd hitch. Prolly won't sag much at all dropping it on the back of a 350!