Factory rated @ 2000 lbs. Of course, that's if the bumper is in tip-top shape and structurally sound. You don't state where you are from, but if the MJ rear step bumper is a 20+ year old original and you are from a rust-prone area, I wouldn't tow a bicycle with it. These bumpers rust out fast.
I tow a similar sized trailer with motorcycles occasionally with no problems towing or stopping, but have a frame reciever hitch, rear disk brakes, 31s and 4.10s with the D44 and an AW4. The key is the receiver hitch, and as airspeed says, very tough to find now for an MJ.