If you are going this time of the year ( June-Sept ) and can schedule a extra day or two then it would be worthwhile to rent a car and go south 4 hours to the Gorge where all you'll need to bring is a 9 m and a small board.
I don't think the sound itself gets much wind this time of year, at least not when I've been there in July-Aug.
You can try here
http://www.seattlekitesurfing.org/fo...wforum.php?f=1
But I think everybody in seattle goes south for the summer as well