One of, it not THE MOST, important things in towing is stopping. The brakes on the Wranglers are very good and have a good swept area for the size/weight of the Wrangler. However, it is still critical that the brakes on the trailer be capable of sliding the wheels on the trailer. If they can do that, then the trailer is not adding any stopping distance to the vehicle's.
If not, then you better go to a tow vehicle that is at least 1.5 times the weight of the towed vehicle or has excess braking capacity. From my experience, any towed vehicle over 1500 lbs should have its own brakes, but that is a personal opinion. I don't believe in surge brakes for several reasons, one of which is that you cannot use an equalizer hitch with surge brakes and any trailer requiring brakes should have an equalizer hitch setup also.
The 2nd most critical thing in towing is the hitch setup. There are a lot of opinions and judgements about towing with the short wheel base of the YJ. These are true and justified with a normal ball hitch only, or even an equalizer hitch without sway control. Once you go to an equalizer hitch with adequate sway control the short wheel base is largely negated. BUT I don't mean a normal friction, or shock absorber, type sway control. I mean the ones that will actually apply pressure to force the tow and towed vehicles into alignment. The only true one I know of is the Reese.
Without the sway control, I don't believe that any trailer should be towed that is longer than the towing vehicle.
Also, the YJ places the ball of the hitch very close to the rear axle. That shortens the lever arm that the towed vehicle applies to jack knife the rig.
Only about 20% of the tow factor is actually related to the engine/transmission/axle ratio factor. Most of that is just to keep up with traffic.
While it is much more convenient to have an automatic, most are not conducive to towing unless you have plenty of power to spare. The gearing of the automatic and its ability to get into the right power band of the engine are problematic.
It also depends on if you will be towing primarily on flat land, or if you will be towing regularly on steep roads with winding turns.
Even the 4 cyl, 2.5L, 5 speed is capable of towing safely far in excess of what the factory attorneys publicize. However, it must be set up correctly and driven according to its power band, etc. Those guidelines are just that. If you compare the ones in the US to those in seveal foreign countries, you will find the US to be far less for the same vehicle. That is especially true when you get to the diesel versions of the same vehicle that are available in foreign countries and not in the US.