It's been done before, and I'm sure it will be done again... Just not necessarily the way I did it
Being a machinist and having access to a manual mill can be a good thing at times
After extensive searching, I found several links to people using conduit clamps to hang there Hi-Lift jacks behind the rear seat. I even found 1 reference to hanging it at the top of the roll bar. Since my dogs use the Jeep for transportation, and since I run without a rear seat, I opted for the high approach.
I had originally mounted my jack using the conduit hanger but I noticed a fatal flaw in the design. There's a nice fairly sharp bit of metal sticking straight up on one side, and straight out on the other. When I put my soft top on, I fear that it may eventually either wear thru or tear my top. Not gonna happen on my watch. Not to mention the security aspect of having 1 very accessible bolt per side holding the jack in place.
Another thread had mentioned Collar Clamps, so I picked up a set of 2 1/4 split collar clamps from MSC industrial and set about modifying them. I drilled and tapped then for a 5/16-18 all thread rod to make the basis of my new hangers. I slid the roll bar padding back and installed the clamps. You can see how there's nothing really for the soft top to catch and wear on.
Then my mind turned to security of the jack. Since the collar clams use allen bolts, I pointed them twards fixed points on the jack to make it harder for someone to unbolt the clamps. I also bent some 3/16 plate steel to make a locking system.
Nice and secure with a Master lock. No real way to take it down without taking the lock off. I know, locks are only a deterrent, and if someone really wants it, they will get it.
Then off to the next problem. With the jack mounted high during the early testing faze, I was bouncing around in Hollister Hills when I heard a loud crack. The jack head and handle had slid up the jack and the handle had smacked the glass side window! Thankfully it didn't break it and I was able to drop a screwdriver thru the hole in the jack to keep the head from sliding over. As a more permanent fix I mad this little assembly out of 3/16 plate. It served 2 purposes, 1 - It keeps the jack head from sliding, and 2 - It actually quiets down the rattling of the jack. You can see the installed assembly in the first pic just above the label on the jack head.
So far I'm happy with this arrangement, and I can't foresee having to change it again. If I should decide to relocate the jack to the back at a later time, it's as easy as just moving the collar clamps.
I now have the ability to run my hard top, soft top or bikini without having to worry about moving my jack.