Why sell the fucking Island?!
You'd be better moving libertarians to it.
Every place already is under the control of some Local Government or other. If that were not true then of course we would simply go there and form our own libertarian paradise.
The island is in Tampa Bay, subject to the jurisdiction of the Hillsborough County Government and the Florida State Government. Moving there would not solve anything, since first off the County would not allow any of us to build anything there and second they would still enforce their evil Laws against Prostitution and Drugs Handling and Incest and Price Gouging.
There is no way that libertarians will ever ever ever persuade a majority of Americans to give up their pleasure of telling their neighbors how to live their lives. The current system works exactly as the vast Majority want it to work, so there is no possibility of rousing a disaffected populace against the oppressors - the oppression is one of a Majority against a Minority, so your father's revolutionary notions won't work here.
The only solution is to go to a place where we can bring enough libertarians to outvote the shitheads so that they can no longer control the local Government. In New Hampshire, that means a Town - preferably Grafton or Ellsworth, low enough population that we can defend ourselves against evil enforcement of evil Laws by voting for public officials who will not enforce the evil Laws and will not pass new ones. In the West it would be a County, say Crook County WY or Loving County TX. This is because of the way NH and TX and WY set up their Governments - most places it's the County you have to worry about, some places it's the Town, in places like California you're best off controlling both a Municipality and the surrounding County.