Jeeps never cease to amaze me. I recently was part of building and driving a float for my kids' school in a local parade. We had a '92 YJ towing a 29' trailer. We estimated about 2000 lbs on top of the Jeep (with framework and the cabin shown below) and at least 4000 behind it (metal top trailer). Then we added 60 second graders at an average of 60 lbs a piece (= ~3600 lbs). With me and all the associated safety equipment (extinguishers, a couple spare tires, etc) and excluding the weight of the Jeep itself, I estimate it was pulling right at 10,000 lbs. Total distance is about 15 miles (from build site to the parade, the parade, then back to build site). Dropped it in 4-wheel low and just let it crawl. Got warm in there, but the engine maintained right about 215-220 degrees.
Ran like a champ. (and we got 2nd place in the parade