2015's have a 5K hitch, with an Allison 2500 transmission
2016's could be ordered with either a 5K or 10K hitch/transmission
2017's all have a 10K hitch, with an Allison 3000 transmission
The upgraded rating is due to both the hitch, and a heavier duty 3000 transmission, versus a 2500 transmission.
I think you'd be overweight with a 32K model, pulling that load.
DaveB, Raleigh, NC
2015 Tiffin RED 33AA, w/Honda CRV
VMSpc, Magnum BMK/ARC50