Got this installed the other day. 4 wheel parts dropped the tank a little to get it in there. Will have to take a few pictures of it and post them here.
Personally, I was kind of skeptical about how it was going to work since I'd never seen one in use. The technicians hadn't appeared to have installed one before and they were also kind of skeptical. But by the end of it, they were showing me how to use it without busting fingers and seemed to like it pretty well. And the design is kind of clever.
The rear seat belt buckles fit through slots in the metal floor and are fed up through the rear seat when you want to use it instead of the trunk extended to its full dimensions.
Of course, with the trunk, you open the thing when it's extended and you are always staring at a pair of seat belt buckles coming up through the floor and in the storage space (same deal probably with full trunks with no floors). But the small space loss there from the belts/buckles hasn't effected the usability on my end as yet.
Obviously doesn't have the space of the full trunks with the back seat removed. But if you have items you need on hand that the instatrunk or insta-trunk-sized lockbox can't fit, don't have the space in your place to store a removed back seat and/or have actually found yourself regularly using your SWB Jeep to haul 3-4 people on days off, the Tuffy extended trunk may work for you. Will see how well I like it after 6-12 months