My biggest concern would be weight. A Tesla model S weighs over 4600 pounds, and that's a plastic car with no real frame or axles. A Wrangler with batteries would be heavy, even if you lost the engine and drivetrain weight. Another concern would be the charge time, and distance available when off road. I would guess that you may only get a few hours of wheeling between charges. Also I think special precautions would have to be taken to protect the batteries from damage. Lithium ion batteries don't like to be punctured or crushed.