If you wanted to sacrifice the back seat, you could put lockable storage containers or a kitchen type thing on the sides. The only problem then would be that the storage in the back would be pretty skinny.
I've done a bunch of concepts and even some implementation of some storage ideas.
Here's one concept which would turn the entire cargo area into a work truck with swing-up diamond-plate side panels:
That may be a wacky idea, but here's one I have implemented and it's much more practical - an LJ "trunk box", fitted exactly to the cargo area of the LJ:
It follows the slope of the rear seat, and it's about as high as the top of the tub, so it's got way more storage capacity inside than anything else on the market.
I may be getting a short run of maybe 10 of these boxes made up, so if anyone's interested let me know.
Jeff
Oh, almost forgot, here's another storage idea I've been working on - storage nets that go along the side rail of the tub. They attach to the hardtop mounting holes, and are adjustable so they'd fit any open Jeep from the CJ-7 to the LJ: