May I recommend mesh boat seats? Nothing against the Recaro's, but they're not designed to handle stuff like that. If you're the handy type (and it appears you are), then you should be able to fab up something custom that will work. Here's just 1 example of what I'm talking about:
http://s3images.coroflot.com/user_fi...Kz5zJhD6AD.JPG
Mesh--so it breathes--and it's marine-grade, so you won't have to worry about water damage.