Here's one I want, but good luck getting one. I think they are having problems with manufacturing. I've called and emailed, no response. They look like they'd be great. There is another member that has contacted them and actually spoke to someone. Anyway it might not help, but if you would send them an email about your interest in their product, If you are interested.http://www.shorelinepro.com/addaseat.asp
Check out their video.