The Trackers only have a 1000 lb tow rating, and it has little to do with the pulling power of the engine. The problem is that the truck is so light, and has such a short wheelbase, that a heavy load will push the truck hard enough to make it swap ends on you. A heavy load will actually try to pass you on a downhill, and pull the back end around sideways.
I pull a lightweight camper with my Tracker, and I can feel that we are pretty close to the limit. A 4dr may be a bit more stable, but the added wheelbase is probably not enough to make towing a trailer with another Tracker safe.
Someone else on this forum has towed a Tracker with a Tracker on a tow dolly, with no problem, and I am sure he will chime in with his experience.
But, a trailer is a bit different situation with the balance of the rig. I was in a Jeep a few years back, towing a trailer with another jeep body (no frame or drive line) in it, and we almost lost it on a downhill. All the driver could do was punch it and hope we could keep ahead of the trailer.
A tow bar rig may be safer for you.