Add-ons are a pretty huge security risk, though. Someone was just posting an article about how tempting it is to sell out with your extension, and how many offers you actually get.

And I've already been burned once, and it's not pretty. Also nothing you can do against this.

The best solution is actually not Firefox, but Mullvad. No need for extensions, based on Tor Browser and can be bundled with a VPN that's full of other people using the same browser - so you have exactly the same fingerprint, and they can't tell you apart. Not by extensions, not by IP.