The OP asks how much can he pull ..not how much load can the truck carry. Big difference.
The '11 2500 chassis sure won't have any issue carrying 3000-3200 lbs in the bed however 11900 lb trailer is a lot of weight for a smallblock.
I pull a 11200 lb 5er with my 2500 Dodge/Cummins/NV5600 6 speed manual with 325k miles on the odo.
I made a living pulling heavy GN trailers (25k-32k gcw) for several years with the old 454/460 big blocks massaged by Crietz automotive (tow motors) to around 300-325hp and 450-475 torque. For my use I wouldn't be comfortable towing that much weight with a smallblock.
I would guess if the truck was designed for 150k miles at max loads it would make it 145k miles before 1st over haul.
You also will need a good Maintenance schedule operating at those weights.