Ok, I think I found audio. May third, 1973 Zep sound check. About 9 minutes in, they play The Rover (two years before its release on Physical Graffiti). Even on my iPad speaker, I can tell that isn't his jazz or his SCPB. The timing is right, just a few days after the France show where you can see him using it. I mean, I would not be my left nut that is the Bass V, but I'd bet a sizable amount of money.
It sounds a bit hollow and honky to me, and as someone pointed out, pickup placement was not optimal and as such, they didn't sound great. This seems to back that.
They play Night Flight too, also from PG. Cool.
So, yeah, bass V is a cool oddball. Would love to have one and string it like a modern 5.