Originally Posted by FFV8
What you need is a Dan Henry sling seat.
Dan Henry was one of the modern bicycling pioneers. He invented the sling seat to bring more people to the sport.
You can't buy one off the shelf. At one time a guy tried to market them under the name "Bummer".
You can however make one yourself very easily - probably why nobody was successful selling them. All you need is a old set of ram's horn type handlebars, a neck & some fabric:
Be prepared for some snide BS from a few fools, and enjoy the lawn chair ride.
That is cool. Would be really comfortable and look awesome on vintage looking build.