I love this board too, but I am a lightweight at about 70kgs, so I use the Kode 86 in marginal wave or bump and jump conditions, usually with a 5.2 or 4.7.
And for these sail sizes, I use a Chocco Starfish fin at 22cms.
The Starfish shape is a crossover profile, similar to an onshore wave fin, but with freestyle pretentions.
Since I put the fin in my board, it has never been out!
For heavier sailors on the same sails you might want the next size up.