I'm pretty sure that Cherokee's are bigger than your Jimmy.. remember the Cherokee also comes with a V8 option.
as far as towing, I just looked it up and the max towing is 2000 lbs... the V8 is probably higher, but if you're looking at the inline 6, I wouldn't tow twice the recommended weight.. remember, getting rolling isn't the issue, it's going to either be, what your towing weights more than the truck, so it's gonna blow you EVERYWHERE and stopping...you can't expect brakes to stop you and twice your weight also...