We are working on single family  seastead design that can optionally have tension legs like a little oil platform.
This makes it really stable in normal Caribbean waves, particularly if in the lee of and island.  It is not
necessary to be in a harbor with this method.

We think we will be able to put screws into the sand and pull down on the structure in 15 to 60 minutes,
and about the same to take them out.

It is not necessary to do this, as the seastead will already be more stable than normal boats,
but it would allow anchoring in places that might not be practical otherwise.

The question is how will various countries in the Caribbean view this legally?

Many have rules about permits for "permanent attachments to the sea floor" but if we are only staying
at any given spot for a few days they should not view it as permanent.

I think there are some "helical screw anchors" that are already used on a non-permanent basis.
Have there been many of these?
When using a regular anchor a chain drags across the bottom causing more disturbance than use of a helical screw,
so screws might actually be preferred by regulators at some point.
Have people doing this currently run into any legal trouble?

Do you think most of the time a regular anchoring permit will be viewed as enough to cover this?

Do you think countries will want to set up a different type of permit?

I suppose it will be necessary to just go to different places, explain it, and see what they say.

Any insight you can give on the way to navigate the legal issue of using tension legs in different 
Caribbean countries?