I thought about relocating mine into the vehicle a couple of times. That was due to planning out in my head how I'd want to put an air tank and some compressors in that area, to hook up an air bag suspension
For securing the spare inside, I kicked around a few ideas of using the factory tie down points, and rigging some sort of harness or bracket for the spare. Granted, I've got an EXT, and have removed the 3rd row seats, so I have a bit more space to work with. But that's an option.