My uncle had one. 03 DRW 5.7 quad cab automatic. He towed a large fifth wheel camper / car hauler with his Superbird in it. I'm gonna guess 11000-13000lbs.
I rode with him from S.C. to the Nats in Columbus in '04. Lots of West Virginia hills along the way. It did it at 9 mpg. The motor is heavy duty enough to do it. But there were some times I was cringing as it was turning 4500 going up hill to maintain speed. It didn't get hot, just burned a lot of fuel.

For what you do, I think it will be fine. There have been plenty of 360s in ton trucks over the years and the Hemi will do it better than a 360.

With that being said, he now has an 07 3500 Mega Cab 5.9 Cummins that sits because of diesel fuel prices.

Since you are looking used, replacement parts, including the motor will be a whole lot less for the Hemi versus the Cummins. The front end will stay together better (less weight). There are benefits.