you need a full 4/3 at minimum for Crissy and should be a good kiter. Just ask locals for advice if you go there because the currents and wind conditions can be unusual and dangerous.
If you can, drive out to Sherman Island in the delta. It's warm and usually great wind with some fun flatwater and swell. Kitopia is a great school out there, or try www.kitethebay.com
for lessons in the bay.
Watch the fog, if it's super foggy in SF and nearby, then Sherman Island will be going off. If the fog is all the way back at the coast you might be better off at 3rd ave (foster city)
hope that helps