Once z-levels are implemented, the OBVIOUS best use for that technology would be allowing us to stack cars on top of cars, and then put a cargo full of cows on top of that.
Actually - this would probably be gay, but gay is beautiful - z-levels could be used to more accurately portray hulks. Instead of one tile, they could have a 3 tile radius, and 3 tile z-level height, which you whittle away at with your makeshift crowbar.
Hulks would then be immune to all guns, melee weapons besides crowbars (you’re prying them apart, duh!), and thrown matchbookes, sunglasses and baseball hats. Just cuz.