Seems to me that you are going the public route.
If the Free State Project (FSP) became a PMA, or formed a PMA in certain areas of itself, couldn't they use the legal advantages of a PMA? Wouldn't a properly formed FSP PMA bar State officials from messing in all kinds of free life of the FSP people? Wouldn't this encourage many other people to join the FSP? Once the FSP PMA outgrew the State in population, wouldn't the State then become the PMA? The State, being a public PMA (whatever
that means), would still maintain all the "rights" of State... such as protecting the FSP PMA in certain ways.