I think your best bet would be to go to a dealer that has a KJ on the lot, find one at a local dismantler or ask around your friends and acquaintances if anyone knows someone who owns one you can sit behind the wheel of to test the fit.
Even if someone here says, "i'm 4'8" and it fits fine for me," they likely don't have the same length of legs, torso or girth, so the seat-to-pedal-to-steering wheel will be slightly different. You won't know until you try it for yourself.
If someone came up to me at the parking lot and asked if they could sit behind the wheel for the same reason, I'd let them. Of course, my mind could be changed by the way they ask, the way they made me feel talking to them and other factors. And I wouldn't let them drive or even be in the Jeep with the key in the ignition. I'm not that trusting.