In my 80 my favorite place was also on the rear wheel wells, I used the holes left behind by the 3rd row brackets to attach it with bolts. I took a 60" high lift then cut it down to 57" to get it to fit there... worked well but as you say wasn't that fast to dig out, as it was usually buried. Plus I would have had to dig out the base from the tool drawer in back, which brings up another issue- if you have to open up a swing out to remove your jack, make sure you're not stuck with your back end against a tree or something. But at least it was clean in there, and I liked where the weight was. And it made for a cool divider for gear behind the back seat, in front of the drawers.
On my 100 I still don't have a good spot. I have tried a few roof rack locations but don't like any of them, and am paranoid I'm going to slip and put the jack through a window. I tried on the bull bar across the two top light tabs, but don't like how it's in my field of view all the time, and how easy it is to bump into. If I had a swing out I'd likely go that route, but I don't, so alas it's leaning up against the wall in the garage right now.
82 fj40, 99 uzj100, 06 gx470
97 DR650, 05 525EXC, 06 TW200, 89 TW200, 09 TTR125, 07 TTR90, 07 CRF50