Ram 2500 6.4 Hemi Towing a Fifth Wheel

I've got a Cougar 29rks that weighs 8700 pounds dry. We loaded it up and took it on a 990 mile, one way trip, from Michigan to Myrtle Beach last week. I would guess we were pushing 10,000 pounds fully loaded. The 6.4 handled Michigan and Ohio amazingly well. I kept it between 65 and 70 mph. It stayed in 5th gear almost the entire time in these two states. Once into the mountains, I found it worked better to shift myself and drop it into 4th before we started to climb. Sometimes it would drop down into 3rd. Never did I feel like I couldn't maintain speed if I wanted to, however, I never pushed it too hard. I'd pick up speed going downhill and take it pretty easy going uphill. On the way down there, we got 10.4 mpg, hand calculated. I was very happy with that. On the way home, I used the same driving habits, however we drove into quite a headwind in Ohio and Michigan. We averaged 9.4, hand calculated on the way home. Overall, I was EXTREMELY happy with how the truck handled the load. No, it's not a diesel, but we thought it did a great job.