Thanks for your reply, Stik.
I'm talking about the horizontal version against the base of the bench seat. I can't quite wrap my head around how such an arrangement could work with the hump.
FWIW, I'm also puzzled that it is described (in several separate accounts) specifically as a 'case' rather than a rack. That seems a fair bit of structure to be putting down there, unless it was somehow built into the seat itself.
Thanks again.