I would think a U-haul car trailer would be fine. They are rated to carry about 5000 lbs of vehicle. One limitation you will run into is that the hold-down straps that they have, which are designed to go over a car's tires, won't go over your tractor's rear tires. You will need to confirm that you have tie-down points on the trailer (you can almost certainly improvise something) and ratchet straps or chains of sufficient capacity, at least for the rear of the tractor.
For tie-downs or chains, you will want a working load of at least 3000 lbs, so if you go with ratchet straps, you'll need the 2-3" wide 10,000 lb breaking strength ones.
As long as we're at it, you'll want to make sure your tow vehicle is good to go. The trailer itself weighs about 2000 lbs, plus your tractor and you're at around 6000 lbs. What's your tow vehicle's capacity, and have you confirmed that all of the components of the tow package (hitch, ball mount, and ball) are rated over 6000 lbs? Are you going to need a weight-distributing hitch to achieve that tow capacity?
