Hi Vic,
I guess I am Johnny Come Lately on this interesting weight issue. I looked up your truck (2014, 11,700 gross, Cummins, Aisin, 6.4 bed, crew, and 4x4) in the 2014 Ram brochure. Your payload is 3950 (page 37 of the brocure) that puts your truck around 7750 pounds empty. That is about what my Ram weighs empty, also. I think the Aisin is heavier than the manual or the 68RE. As to the tailgate weight credit when off, I consider that a 'wash' since I have permanent Tork Lift camper tie downs (so do you). They probably weigh approximately the same as the tailgate. For weights water is 8.3 pounds per gallon, propane 4.2, and diesel 7.1. It is easy to have more than 300 pounds difference in weights just with how much diesel and water you are carrying at a given time. As to the previous comments about being under 80 percent of gross, that is almost impossible for most carrying a truck camper. In fact, looking at your numbers it is good that you opted for a one ton as the 2500 Ram (Cummins, 6.4 box, crew, 4x4, auto) maximum payload is 2250 pounds, more than 1600 pounds less.
Based on the sticker of 3668 pounds, you have about 280 pounds of options, accessories or stuff in the truck (3950-3668) So your truck weight is probably with full fuel (210 pounds +/-) about what you calculated. Pop up truck campers sure have gotten heavier from the days I owned an Alaskan camper.