You can't escape the government (or more specifically, "a government")... not while you're on Earth. The best and easiest way to do what you want is to identify the persons/companies in power and persuade them to give you that freedom, offering something useful for them in return.
It's really not that hard, and easier than establishing a new nation in the middle of nowhere, as attractive as that might sound...
It's funny you mention that - we studied Sealand as part of my Public International Law course about 5 years ago, and that's pretty much the conclusion that we all came to. The "best" things a country can do are only worthwhile with international recognition. Even Tuvalu (population c.10,000) gets its own TLD (.tv), which has been its prime source of income for some time.
Even more specifically, the US government. There are many governments on Earth you can escape from, but not the US. If they want you bad enough, they'll get you.
It's really not that hard, and easier than establishing a new nation in the middle of nowhere, as attractive as that might sound...