With my '89 Accord ( 2.0L FI, 5 speed ) I regularly towed a utility trailer. The heaviest load I towed was about 2300 lbs in the trailer + the weight of the trailer. ( 489 pounds empty ) While I don't recommend anyone trying this, unless they really know what they are doing and are conscious of how to load it properly, it towed it just fine in 4th gear. Stopping distances are increased, and too little weight on the front tires can cause a serious safety issue. Engine temperature was never an issue, however the transaxle did get really warm.
With 1500 pounds total ( 1000 lbs in the trailer + trailer empty weight ) there weren't any issues, and it was much safer, albeit still over the recommended towing capacity. With the low profile popup tent trailer, it was not a problem to climb a 7% grade with the car, and still maintain speed.