Not a dumb idea. Well, I hope not because I've given it much thought.
For the cab design, you don't need to be a furniture maker. You just need a cab that is symmetrical from the side. I'm thinking like the Tron cab.
I don't have my (sad) drawings with me at the moment, but I believe I came up with a way to use two systems as separate machines or to share the monitors as one game. It would require 2 ipacs, a KVM and if I recall correctly, 2 PCs.
I'll have to find my drawings and revisit this.