So finally pulled the trigger on this. I chose NOT to cut into the rear fender wells, and opted instead for the Tuffy under seat storage drawer; their part #130-01 and install kit part #026 (for CJ models). Overall this is built quite well in terms of the materials. It is all steel with roller bearing slides and reinforcements where needed (seat belt mounts, seat mounts, etc). It has a locking latch with a key and a push button release. But it is a pain to fit in and get it all lined up. And the kit is made for a stock CJ rear seat. I have a fold and tumble from Besttop, so some slight modifications were needed. Here's my starting point with the rear seat and Rugged Ridge rubber mat in place. So I started by removing all that, including the mounting brackets and center belt buckles. You can see my access panel for the fuel sending unit in the floor.
Next was to get the drawer housing (with drawer removed) into place and bolted down. You're actually supposed to mount the seat to the housing before installing in the Jeep so you can access the underside for the seat mounts. I had to drill two new holes for the center latch for the fold and tumble seat. That was the only mod needed to make this work without the stock Jeep seat. You can see my center latch mount a few inches forward of the provided holes on the housing. The rear seat is about 4 inches higher than normal now, which I wanted anyway. So extra bonus. I did get lucky however. I forgot to make sure the seat would clear my roll bar mounted wakeboard tower speakers when folding it up/down. But it just fits. You can also see where the side belts mount on top of the box since the box uses the existing threaded holes in the tub where the seat belts were previously. This is a real pain. The bolts are installed from the inside of the drawer housing on each side, behind the slide rails. So you are working blind by feel only. In addition, the drawer housing is not tall enough to allow a ratchet and socket on these bolts, and a wrench can't be used due to the rails. I used a deep socket with a hex on one end (5/8 spark plug socket) that I could then use an open end wrench to turn the socket. The front (didn't grab a pic) uses a pair of supplied brackets in the install kit and some longer bolts to mount into the existing seat mounting holes in the tub. No mods needed at all there. And of course then I bolted down the center seat belt buckles to the existing reinforced hole in the housing and added my cargo mat back in.
Next I installed the drawer - and discovered a problem. When opening/closing the drawer, it rubbed on the tailgate latches on both sides. Now if I pushed down on the tailgate and up on the drawer at the same time, kind of forcing it a bit, I could open/close it. But something ain't right when this thing is rubbing the latches. Solution? Removed the two rear bolts that I said were a pain mounted from inside behind the rails. Added two washers under each as small spacers and then reinstalled the bolts. But now the bolts had to go through their existing washer inside, the hole in the drawer housing, then two washers underneath, then find the threaded hole in the tub - all without any ability to see what you're doing to make this all go in. But a few choice words and skinned knuckles and voila - the rear of the housing (and now the drawer) are just a few millimeters higher and no longer rub when opening/closing the drawer.
So how big is this thing? How much actual room is there? The inside of the drawer is about 27"x29"x2.75". And I still have the same amount of space behind my rear seat for other items (winch gear bag, etc). And none of the stuff on top of this drawer assembly has to be moved to open the drawer. Just swing out the tire carrier and lower the tailgate to access all of the contents.
Now with it all installed, I ran into another problem. When I went to close the tailgate, I can't. The tailgate hits the handle on the rear of the drawer. There is a push button latch that comes within about 1 millimeter of the tailgate when closed. But the supplied handle sticks out a few millimeters even further and prevents the tailgate from closing. I re-checked all the mounts and am sure it is mounted in the only place it will fit based on the front mounting brackets using the existing seat mounting holes. So it can't be moved any amount forward to allow the drawer handle to stop hitting the tailgate in the back. So three options: (1) leave the handle off. This is no good since the drawer fits pretty snug and would be very hard to open with no handle to grab; (2) cut the handle down shorter and re-weld the mounting tabs to it to reduce how far it sticks out; (3) make a different type handle (rope or strap) this is flexible when the tailgate pushes against it. I went with option #2 for now, cutting the two side tabs off the handle, shortening them a bit, and re-welding them back on. The handle is tighter against the rear of the drawer where you put your fingers in to grab it, but usable. If I get tired of it, option 3 is next. Some nylon strap or small diameter rope put through the mounting holes where the screws go with knots tied to hold it in place. Maybe even a small plastic tubing on the rope for a grab handle.
So I have a small tool kit (wrenches, screwdrivers, pliers, sockets, etc), my jumper cables, lug wrench, winch controller, rope, etc all in this drawer - and there's still room left. And since it locks, plus is bolted to the Jeep with the seat bolted on top of it, little chance of theft when parked somewhere with the top/doors off. Overall I'm satisfied with this option. No holes drilled in the Jeep. No cutting anywhere needed. Used all stock mounting locations. And my fold and tumble seat still works fine by only drilling two additional holes in the top of the drawer housing. After some fighting on hole alignment (common on old Jeeps) and dealing with a few minor issues (rear handle and tailgate rubbing), I believe this to be great option for secure storage in a CJ.