Seriously no need for that with Ammo-o-Matic. You can camp almost anywhere with the Wunderwaffle as long as you have a way to run to the Ammo perk machine. You can get to insane rounds camping with the Wunderwaffle. Also the catwalk by teleporter seems to only path zombies up the right stairs (like it did in The Giant). So as long as you don't go on the second set of stairs all the zombies will file up those stairs and along the catwalk making it an extremely easy camping spot with or without the Wunderwaffle. You also have a super easy escape and path to the ammo-o-matic machine.

the ledge by stamminup is a great camping spot as well.