I've pulled a 31 fountain down the road with a 95 2.5L YJ.... I wouldnt use it as my tow rig, but it has the power to pull.. It just doesnt have the braking system or the stability of a longer wheelbase vehicle.....
If you find yourself at a bad ramp trying to pull the boat up could be a chore. Mostly depends on the weight of the boat, that wrangler is only rated for 2000lbs so if your boat is lower then that, have at it. just don't expect to beable to hit the interestate with it..... A 6cyl will do better with the same mileage, but then again i wouldnt go down the interestate with it....
give us some more info on the boat.. if its light and won't push the jeep around TOO bad then you might could pull it off...
If you want to go topless why not find a 6cyl fullsize bronco? They are powerful and have decent gasmileage for what they are, and you can remove the top.