My last truck was the 2014 Ram 2500 6.4L Hemi in my sig pic. I towed a 12k 5er (37' with 3 slides) with it all over and through the Canadian Rockies. I was very satisfied with the performance. I wouldn't hesitate to buy the same truck again for pulling a big load occasionally. I got 7-9 mpg pulling that load, most times it was 8 mpg.
With the Ram 2500, I had 3000# payload, and was under all of my ratings (GCWR, GVWR, GAWRs, and max tow rating) while hitched up. Oh, and there was very little sag and a nice ride (empty and loaded) with the rear coil spring suspension. The pic below is all stock. No airbags needed, even with the big 5er.
Did it use high RPM to climb big grades? Yes.
Did that bother me? Nope. That's where the big Hemi made max power.
![](http://i117.photobucket.com/albums/o53/ib516/RV%20Stuff/20150801_083223.jpg)