Al-In-Zn anode would be better or even risking a magnesium one -for an 'Al' mast that is. For uniform corrosion. 'CP' for pitting (negative polarization) is also benefitial. Crevices are indeed an issue. I also do not see a threat from OH- ions generation as foils moves (Al is prone to alkaline corrosion).
As I am a Baltic kiter - I am yet to find crevice and pitting issues in my gear.
I also doubt that you would find 'real issues' with 316 steel with your 316 bolts in any environemnt. Actually when it comes to corrosion engineering the most important issue is: life expectancy vs. cost of corrosion protection. In most cases even if you would find crevice/pitting issues the best way would be to have a second set of bolts rather than going for a higher grade alloy.
Btw. One corrosion issue you might have missed - and it could be actually prety dangerous is intergranullar corrosion - a bad weld in kiting hook could be very dangerous if it is left in corrosive environment.