Some numbers that I found for an '04:
Curb weight 5,095 lbs.
Front curb weight 2,786 lbs.
Rear curb weight 2,309 lbs.
GVWR 6,600 lbs.
Front GAWR 3,600 lbs.
Rear GAWR 3,900 lbs.
Payload 1,510 lbs.
Towing capacity 5,750 lbs.
GCWR 11,000 lbs.
Max. advertised receiver TW is 740#. The TT has a dry TW of 585#. For a 12% TW @ GVWR (7000#), TW can be 840#. With the kids and dog (?) in the back of the Durango, and you'll hit the limits of the truck rather quickly on all fronts (and possibly over GCWR). As previously mentioned, the short wheelbase of the truck may make towing a 31' TT interesting.