Questions about a 2012 Dodge 2500HD / Cummins

I had a 2012 Ram Diesel with crew-cab and long bed with a six-speed manual. Thought it would be a great truck for us, but after towing our Jayco HT 26.5 RLS to Zion and back came to a different conclusion. The diesel is a bit underpowered since it has the manual and is not the HO engine. When we took our trip to Zion, we got around 11.9 on the way down there, drove around a bit to St. George and Bryce Canyon unloaded and then back home. When getting home, overall mileage was down to 10.9 and a subsequent fill-up and three trips to a lake about 40 miles away yielded around 10.2. When I hooked up our boat behind the FW was when I really felt the lack of power in this engine. Also, and this is a personal problem, when backing up with the manual, you have to keep both feet on the floorboard to work the accelerator, clutch and brake when backing looking over your shoulder. This was more difficult to do than I wished for. Also, my wife was unwilling to drive the truck with the six-speed manual. So, we traded back to a GMC crew-cab, short bed with D/A combo. Now, we get, generally right at 12 mpg when towing our boat and trailer together and have gotten as much as 13.6 on our trips. I also no longer feel the least bit underpowered. For what you are pulling, that truck will certainly do a good job, just pointing out what I experienced when buying this 2012 vehicle.