The problem is that we are mixing several different types of goals.
Creating a viable marine-based business based off a floating platform.
Creating a seastead, a sea-based version of a homestead.
Creating a new sovereign state so as to experiment with new forms of government and society.
To achieve #1 you don’t need anything besides a good business plan and something that floats. You could be selling live bait to fishermen in the Keys out of a floating shack made from wood and old soda bottles. You could be delivering pizza to oil rig workers from your sailboat in the Gulf. There is no component of self-sufficiency or autonomy, you are just running a business on the water.
To achieve #2, you need to claim, lease, or purchase rights to a specific patch of ocean, create a permanent structure, and then use your labor to “improve” the area you have claimed or leased. This requires a bit more technology because the structure will have to be moored or anchored or otherwise affixed to a specific permanent location, but nothing that doesn’t already exist. There is no requirement for autonomy or sovereign rights or anything else special, just an ability to “work the land”. This area can be close to shore or on the high seas…the location doesn’t matter nor does the manner of platform you use. All that matters is that you stay in a specific location and improve that location with your work.
To achieve #3, location is the most important thing. You will need to be outside of the influence of any existing State, which means outside the 200nm EEZ and, in some cases, even further out beyond the continental shelf. This structure will need to be a seastead by the definition of #2, because you will need to be in a permanent location (to have any hope of claiming territory and thus statehood) and have to develop the surrounding area (to achieve some form of self-sufficiency and create products to sell/trade for the stuff you can’t make).
These three goals are very different, and I think there tends to be a lot of confusion between #2 and #3. You can have a seastead without sovereignity or “experimenting with new forms of government” or any of those higher goals, but to achieve those higher goals you are going to need a seastead.
Perhaps what we need is a new term for #3 besides seastead. Perhaps “Ocean State” or “Marine State” or “Seastead State”…something that specifies we are looking to do more than just claim a patch of water and farm it.