This motor has 300plus HP, and it only has teh ability to tow 10K lbs?!?!?!?!? yeah right! This setup has better gearing the the 4sp trannies with 4.10'S! I'd pull my 12K equipment trailer with this truck. My guess is a 12K 5w will tow easier yet, much easier than a TT would, due to better aerodynamics of the setup! Frankly, as long as you get a hard sided smooth walled trailer, with no frontbed room slide, I'd go for it! You should be under the axel wt ratings etc too!
Yeah you will be turning some rpms, like 4K going up hills, in the gear below direct, not that the 6sp has a direct from what I understand....still, you will be in 3rd or 4th gear going up steeper hills, probably in the 50 mph range. The only person that gets tired, is one not wanting to hear a motor turn some rpms! My dmax sounds horrible with a 25K total load going up a 4% grade with the pedal to the metal doing 55 at 3000 rpm. Would imagine the same sound at 5K+ rpm in a as rig.
As long as you can stay under axel wt ratings, the truck will handle the trailer fine! A dmax is rated higher, so the truck etc will handle the trailer.
Marty