JonahL said..
Wing and board leash to my harness. Also, wing leash as short as practical and a 10' coiled SUP leash to the board so that if I get rolled in whitewater the board/foil is past the wing. I've been worked in overhead waves a few times with this setup and so far so good except for the stock wing leash that broke. Bungee spectra leash to the wing now
Same, except ... Wing leash longer, in fact I add about 400mm of dyneema to a standard ozone leash. This way I can attach it to my harness belt at the back and have the leash behind my head 90% of the time.