If you can stand it, you might also try a "boogie board." You can pick one up at Wally World in most coastal areas cheap and they are quite durable. Think you could strap on a variety of bags or water proof boxes. Break out the marine sealant and velcro and the sky's the limit. Maybe even attach a Scotty. Board comes with a tow cord too.
Actually, I am looking at a nice Scooby print boogie board right now (my son's). In all seriousness, I think we might just have something here.