Hmm... so an empty shelf with
maybe a spare tire. That's not fun at all...
I'm reminded of a Seinfeld episode -- I could rent out the shelf space to Japanese business-men.
And to keep it lightweight during the drive, I could set up a bunch of hamster wheels back there, so I can run alternator-free. And/or set up an entertaining diorama for my tailgater parade... maybe with cfg83's poke-modders, eh?