Depends on how it's made and what you need it for. Trailers made from a chopped off pickup are pretty common, but how useful it is depends a little on how well they designed the tongue end. It requires a reconfiguration of the frame, and in some cases, lowering of the tongue. Well done it can work fine, but badly done it can flex and crack and generally be a mess. It will be heavier than a regular utility trailer, but of course it will also have a pretty good capacity if you can pull it safely. Pulling is not so much a problem as stopping. There is at least the potential for hooking up the existing brakes with a surge hitch, but if this isn't done it will be a pretty scary tow when loaded. I would not go for this unless it's quite cheap. A heavy trailer can really jerk around a light vehicle like an XJ unless the tongue weight and height are just right. If the tongue slopes up, it will lift up the rear end; on a steep bumpy downhill when you hit the brake, it can jack you right off the ground.