I'm 6'4" and can just barely sleep in the back of my XTerra if I remove the seat bottoms from the back seat instead of folding them forward.
I've been thinking about a sleeping platform/storage solution for a while. I think I want to do a modular system that can be split. This means I can use it when the rear seats are up, or I can install the full console deck and fold down the rear seats if it's just me and my wife. I think if I bring the deck up about 12", I should have enough space to lay down and still have good storage under the sleeping deck.
The rear module will have drawers that slide out and a deck that lifts up so I can have two different types of access. The fitted side panels that will conform to the interior should also lift up so I don't lose storage space for all those little items. The front module that will fit right behind the front seats will have two types of access, a side door to access the space under the deck from the rear doors, and a center hinge to allow the deck to be lifted for more access. I might hinge that at the back, but I'm not sure yet.
All the lifting floor parts will have a length of rope on the underside so I can "hang" it open from either the grab handles or the roof tie-down points. I may also want to put some LED lights in there so I can see what I'm doing.
The top of the sleeping deck should be carpeted and have cargo tie-downs around the edges so my Plano, cooler, and Action Packers can be secured. These can all be placed outside or slid under the rig when I want to sleep.
I haven't built any of this yet, I don't have the tools or expertise. I'm hoping a friend of mine who is into wood working might have time to help me at some point, but he's always so busy that I feel bad asking for more of his time.
I don't know if any of these ideas will work for the Renegade or if it has a fold-flat front seat to give you more space. Feel free to use any of what I've mentioned from my plan if it helps.