In thinking about Cay Sal Bank particularly, I've been envisioning some sort of winch-assisted slipways for docking solutions being built into the seastead.
When looking at securing loads, slippage is problematic. You don't want heavy things to have any play to build momentum and then be abruptly stopped. That causes damage, and often exceeds tensile strength of tie-downs. If you can just prevent the load from moving at all, you're better off. 'Beaching' boats up a slipway above tide and wave surge would be one way of preventing damage during weather. Wind loads can be vicious but simply don't have the same mass as water and aren't quite as variable (or at least cyclic), so it takes massively more powerful winds to do the same damage as relatively minor waves can do, pounding on things over and over in a cycle.
You can only tie boats so closely/tightly to a dock. They need a little play because of water movement under the hull due to waves and tides. If you tie too tightly, you put undue stress on cleats and attachment points when water level drops or rises. But conversely, you also get the hull banging against the dock, and pneumatic fenders can only do so much, they sometimes slip out of place up onto the dock instead of staying between dock and hull. Or they can be crushed flat with enough force.
Even for fairly large boats, you could engineer a slipway that tilts to accept a boat, and lifts to store it level, out of the water. I would use some kind of lock and fill system to use water weight for counterbalance instead of hydraulic rams for ease of maintenance and long term lifecycle. Perhaps you could even build in carriages on wheels/rails that accept a boat hull like a boat trailer does for smaller recreational boats. Something like a light-duty railroad car designed specifically for cradling boats.
Also for Cay Sal, I still think a gravity base makes more sense than permanent flotation. The Hex "barge" with open bottom concept lends itself well to semi-submersible. If mobility and flotation is required to get buy-in (both economically and perhaps legally to get permission to operate in the region, and to remove the structures should the effort fail to catch on or continue) then float the things out there, and then ground them in an ecologically sound manner/place by removing some of the flotation. It's pretty easy to figure ways to pull EPS blocks out from under the thing, and it doesn't require absolute water tight hull integrity to re-float the hex in 50 years.
Casino barges in Biloxi Mississippi are floated in literally inches of water depth, to get around legal rules requiring gambling operations to be contained on boats. They are permanently moored to buildings with an internal connection between the barge and the hotel building, often on multiple stories of the hotel, that the average person never even notices when they walk over it. For serious storm conditions, they temporarily scuttle the barge (flood the buoyancy tanks) to rest on the bottom, close down gambling for the duration, and re-float it with buoyancy tank pump-out after.
Another alternative is the spud barge or jack-up barge concept. Anchoring a numbers of hexagons with spuds and attaching them one to another is a much better solution that multiple anchor lines. Not all of them even need to be on spuds, just enough to provide solid, stable connections for the rest of them.
I think once it's in place, it will become such an accepted feature of the region that there will never be much call to remove it, that it will improve the environment by promoting fish habitat, providing vertical relief that shelters new spawning grounds, etc. I would bet that you'll grow so much new reef around it that no one will be willing to force it to move because that new reef would be damaged if they did.