I think onthespot is kidding. He lives in that neck of the woods and is hoping to cash in when he is healed up. Check out some of his past posts, he knows what he is doing!!!
Sorry about that, I was joking. Okinawa has a big learning curve, from where you can hunt to how to hunt it. In 2012 I had 2 keeper rings from march to December. Once I got it dialed in, I have had a much better 2013. Just keep at it and you will do fine.
You have the dry sand covered how about an excal for the wet and water. Or if you want to stay in the wet sand the ctx 3030 is a great machine. But I guess it depends on price preference.
If you don't mind digging everything the whites dual field is a great machine. I use mine for diving as well. And the Tesoro shank shark is good too.