Re: Double Bike Seat.. Does it exist?
If you had access to a welder, I'd go for a seat off a chinese moped. Those banana seats look pretty hard, but I never seen one up close.
The only thing about the moped seat is you'd need access to a welder to make a custom sissy bar & to get the front end to the seat post somehow.
Used to ride around one of those mopeds with 2 (sometimes 3, one kid was like 13 though) people all over the place. You definitely NEED to be comfortable while you do it. The shape of that banana seat looks pretty unfair to the driver.