If you going to use a kayak with sails etc and do some serious offshore running with the wind, flotation bags or similar items may not be a bad idea. However, the best idea I think is to be in something that you can turn right-side up after you flip it, and by all means do it several times before needing to. And I speak from first-hand experience
Kayak, canoe, recreational kayak, whatever it is. Not only be proficient in piloting it,but self rescues, and any special items you may need for that purpose.
Then ride the wind
Perry