There are many suitable riding areas along the western beaches of Captiva for winds from westerly directions and further south on Sanibel from easterly directions as well. North Captiva looks rideable from SW to W to N to NE to SE on Google Earth. I would expect some wind shadow impairment of wind from N to NE to SE and not a lot of other riders up there. I could be wrong about the riders though. I know guys ride around the Sanibel lighthouse, along Sanibel Causeway and in Ft. Myers. Not sure how many kiters frequent Captiva or South Seas but you may find some. Roy Massey at Ace Performer Watersports,
http://www.aceperformer.com/ just over the Causeway may have some suggestions. Riding off the Causeway can get tricky, local knowledge is recommended.
More at:
http://www.fksa.org/showthread.php?t=2099
Have a good weekend!