Someone here is going to get on to me but I would not sell yourself short on that truck
I am breaking my rule to never comment on this topic, but I have a 2008 Duramax/Allison and tow a 34' HitchHiker II with confidence and every feeling of security and control. We have 81,000 miles on this truck, much of that towing.
We have been all over the mountain west and over many of the major passes which the tow/haul mode proves it value every time.
Now, I'm out of here before I get attacked -- but note my covered map in the signature below.