FWIW:
yeh, you "could" use a metal strip but you'd still need to attach the ground wire from the bridge. Some of the older instruments actually had the controls in a metal container. I've used strips of copper shielding run between pots to eliminate pot to pot ground wires for outboard preamps and it worked fine. The fewer wires the better as far as I'm concerned.
Forgot to mention, it's a wise move to throw down a small piece of electrical tape beneath the pot terminals. Like a shielded cavity, that strip will not only ground the pots but any lead that touches it.