How would a similar extra-legal data haven work today?
Let's say cost is not an issue - some people with deep pockets have things they think are worth it to host outside the law, and will pay you with bitcoin (run through a bitcoin pool operating on the extra-legal territory itself).
How do you get around the fact that all your internet links will be run by companies in real countries subject to legal orders?
How do you get around the fact that any ragtag band of pirates can board and take over your "island" nation? Do you hire a team from G4S to guard your ship? G4S or any other security entity would be subject to laws and court orders, too.
If it's not a ship, but an actual island, you still have most of the same problems. Even if it's populated to provide some measure of physical security (you can't bomb an island with innocent civilians on it without a lot of bad press, not that other governments would need to bomb to shut you down), won't the existing government care more about protecting tourism and/or the interests of the natives before they care about protecting a data haven?
For hosting static data, it's trivial to build a distributed cryptographic system which is arbitrarily censorship resistant. The trivial way is to distribute a large file encrypted, then once it's widely seeded, publish the key. It's really hard to censor a short string, basically as hard as censoring an idea.
For transaction processing systems which need to be durable, I'd go with something with multiple levels of indirection on the network, using links which are locally secure for short periods of time. Sort of like tor/onion routing with hidden services.
You might still put your processing nodes in a concrete fortress of some kind, but they're basically anonymous data processing equipment. Use tamper-resistant technology and the worst that happens to them is denial of service.
The point of having a published high profile physical location (like Sealand) is to claim jurisdiction there, and thus get some legal benefits in interacting with other jurisdictions. To the extent that everything can be done on the Internet, you don't particularly need that.
Further, if you're hosting content that makes governments unhappy (say, WikiLeaks-esque data that casts other sovereign nations in a bad light, or actively hurts their country like a list of undercover operatives), what is to stop them from using their military to take over your sovereign country?
Wars happen all the time, and you have no military of your own.
Let's say cost is not an issue - some people with deep pockets have things they think are worth it to host outside the law, and will pay you with bitcoin (run through a bitcoin pool operating on the extra-legal territory itself).
How do you get around the fact that all your internet links will be run by companies in real countries subject to legal orders?
How do you get around the fact that any ragtag band of pirates can board and take over your "island" nation? Do you hire a team from G4S to guard your ship? G4S or any other security entity would be subject to laws and court orders, too.
If it's not a ship, but an actual island, you still have most of the same problems. Even if it's populated to provide some measure of physical security (you can't bomb an island with innocent civilians on it without a lot of bad press, not that other governments would need to bomb to shut you down), won't the existing government care more about protecting tourism and/or the interests of the natives before they care about protecting a data haven?
http://imageshack.us/f/546/havenco.jpg/