So this is the TJ/YJ "hidden" hitch I'm considering for my KJ:
Draw-Tite Trailer Hitches & Towing Accessories. Since 1946, Draw-Tite has always strived to provide the right trailer towing system for each application. This is why we offer as many as ten different trailer hitches for a single vehicle. Whether it's weight capacity, ease of installation...
www.draw-tite.com
I like that one better than the Curt version since the shackle mounting points are on the very outside and there is a decent chance they'd stick out where the existing tow hooks protrude from the holes in the bumper. On the Curt one they'd be behind the bumper so would be useless unless you cut new holes in the front of the bumper. On the Draw-Tite it might be necessary to do some trimming on the outsides of the existing bumper holes to make those usable. Or in both cases you might want to just cut them off.
This hitch bolts to the top of the stock bumper through the frame on a TJ or YJ. The hitch has 3 mounting holes on each side but only 2 would be used on a TJ or YJ. 96 or later use the 2 farthest holes and earlier Wranglers use the front and middle holes. If it fits on a KJ it would be installed upside down to the 4 outside tow hook mounting points on the frame but I don't know whether you'd use the +96 or -96 holes on the hitch or if you'd need to drill a couple of new holes. I found a post on wranglertjforum.com that gives the width between the mounting points on both a TJ and a YJ - it's 30-3/4"
https://wranglertjforum.com/threads/yj-front-bumper-on-a-tj.72661/ so that will be the distance between the mounting points on the hitch. I had a hard time getting a good measurement off my KJ with the bumper installed so it could be a bit off but I measured 30-7/8" between the outer tow hook mounts so worst case you'd have to die grind or drill out the holes in the hitch 1/16" so not a big deal. I think it's more likely my measurement is 1/8" inch off and things would line up perfectly. As far as the front to back distance between the holes I have not been able to find any TJ or YJ dimensions yet but I guess if neither match the KJ you could re-drill or die grind the hitch. If anyone is in a position to verify any of these dimensions it would be much appreciated. Also, if you see a fatal flaw in any of this please holler.
I'm not ready to pull the trigger on this but I'm about 90% sure it would work. With a 20% off coupon at autozone.com (you need to sign up for emails) you can get the Draw-Tite for $139 and hopefully shipping is free so not a huge loss if it didn't work. I'm not in a big rush and I know someone must have done this if it's actually possible so will wait to see if anyone chimes in.