The "basement" in my LTV is great. If you want to do it on another model, keep in mind that LTV does not mount the spare on the door hinges like so many tire kits do. They're concerned that the weight will harm the hinges over time. Their kit includes a bottom-mount spare tire mount, where the upright folds down to the rear in order to allow the door to open.
I've also seen a picture of their inner spare tire cover that lets the spare be used as a table when folded down -- I don't have one, yet, but it's a clever idea.
In addition to all the carrying space in the basement, I also carry a 20' sewer hose, holding tank cleanout "swizzle" hose and a spare water hose coiled up inside the spare tire rim and held in with bungi cords.
Like What Next, I carry a Weber Gas Go Anywhere grill, tool box, small vacuum cleaner, assorted extra "stuff" and even my satellite dish and tripod (disassembled, of course) in the basement box.