This is a fun post, but it's been done. I think the name of the guy who made the "real deal" was Charlie Deal (or something close to that)--although he didn't build with actual seats--he carved real bodies from real wood to look like toilet seats, & they had properly fitted necks (maybe not so much in the early years). He was somewhere in the San Francisco area. Airplane/Starship had toilet seat guitars back in the 70s, & I think I've seen pics of the guitarist with Huey Lewis with one. I want to say I've seen Elliot Easton or Rick Nielsen with one, but I can't be sure of that. They were high-end novelties that were playable, a lot of them also sounded good--& a lot of irreverent guitarists (especially from the "flower power" era) eventually ended up with one. They were relatively sought after--mainly because Charlie didn't make them fast enough, & supply never met demand (which I guess means there have to be collectors somewhere).
Anybody out there in la LA land, keep an eye open--you might find one at a California yard sale/flea market/pawn shop.