I've got a 2015 GMC Sierra Denali, with a 2014 AF 992 (about 5500 lbs ready to camp) - I traded in a 2011 Denali dually last fall. I also tow alot - 5500 lb boat/trailer, 9000 lb 3-horse trailer, plus some smaller stuff.
There is no issue with my camper fitting the 2015 - I have a spray liner and a rubber map, all is fine. I can't speak to the 1150 but I assume it fits similarly if not the same.
I've found that the 2015 has slightly softer suspension than the 2011 - it sagged about 3" with the camper on, vs about 1" for the 2011. I put upper Stableloads on the 2011, and that worked fine although I had to cut them down by about 3/4" so they wouldn't hit the spring pack when empty. For the 2015, I put in lower swing-out Stableloads, but the truck still sagged about the same (but was much more controllable). I ended up putting in airbags to level things out, which works great as long as you keep enough weight on the spring pack.
My weights with the 992 loaded (I think it's only a couple hundred pounds lighter than the 1150, if that) are:
5000 steering
9050 rear
====
14050
So, about 1000 lbs over the 13,025 GVW, but it handles fine. So far this year I've done 2 round-trips from WY to GA (1900 miles each way), towing the boat half the time, and it rides and drives well.
- Clay
