There are a couple normally accepted guidelines for towing. The first is that, the first 110" of wheelbase allows 20' of trailer. For each additional 4" of wheelbase, you get 1' more of trailer.
The second guideline is that the distance from the coupler to the rear trailer axle should be no more than twice the wheelbase of the tow vehicle.
The Liberty's wheelbase is listed as 104.3, so we don't even pop up on the first guideline (there's a chart on RV.org). But, using the second guideline, we are well within the bounds of reason to tow a trailer that has 208.6" (17.38') distance between the coupler and rear trailer axle.
Definitely get antisway/distribution setup.
I would suggest trailer brakes on anything over 10' long, or weighing over 1500lbs.
A class III hitch can handle between 3500 and 6000 lbs gross trailer weight (GTW) and 350 to 600 lbs tongue weight (TW). The highest rating on any Liberty ever produced is 5000 GTW, so I would stay under 5000 lbs GTW and 500 lbs TW. There is a great little method for measuring TW.
None of these guidelines are written in stone, nor are they law. But I would be wary of exceeding 500 lbs TW, or hauling anything over 26' long for any length of time.