There are already private cities and other autonomous regions. That's one option. I don't like isolated areas, so sea steading and even small islands seem impractical to me. Liberland is working on purchasing or leasing lands from already existing nation states as another option. You have fairly independent groups like the Cossacks in Russia to consider as well. For their services, they are pretty much left alone to govern themselves. We are definitely far away from leaving this planet, so I hope to solve the current problem with options like the ones I just listed. Perhaps there are other options as well that we just haven't figured out yet though.