Ah yeah making a box would be nice to level out the rear for an air mattress or even transporting something flat like a tv. Plus it would give you some storage space under it for the quarter panels or maybe the freedom top for those with the standard hardtop.The rear seats on my son's Rubicon JKU fold flat so the seat backs are on the same level as the rear compartment. He is able to put an air mattress in there for camping etc. I presume a non-4xe JLU is the same or similar so the rear seats fold flat. (someone else will have to confirm this for me...)
In our 4xe, the rear seats don't fold the same way as my son's JKU. The seat bottom flips forward and then the seat back folds down into the space where the seat bottom was. In that folded state.....the back of the rear seats are about 3"-4" higher than the rear compartment floor. I am looking for some aftermarket or custom box that can ride back there to get everything to the same level so I can use the air mattress the same way as he does.
I am thinking about making a custom box that is able to store the side quarter panels from the hardtop. Our 4xe has the electrical retracting roof so the hard shell doesn't really come off all that easy. The side panels do and they provide a bag to store them behind the seats but I am thinking maybe a floor box would work better for me and make it so I would have a level deck when the seats are folded.
I will get you some photos when I get home....