I wrote up our security procedures here: https://news.ycombinator.com/item?id=37346620
The reason Tails isn't an option is because, as others have mentioned, there have been Tor browser exploits which reveal the IP address of the Tails user. While this is unlikely for our case, it's important to approach security from first principles with threat modeling. An attack from the FBI may seem unlikely today, but both Silk Road and one of its successors were taken down by mistakes they made when setting up their site. Learning from history, if you're not careful early, you're in for a surprise later.
Case in point: When I started Whonix Workstation to post this comment, the Whonix Gateway VM failed to boot. So when I tried to start Tor Browser and go to https://news.ycombinator.com, all I saw was a connection error. This kind of layered defense is essential if you're serious about staying out of jail.
Realistically, you'll likely dox yourself through some other means: sending Bitcoin to your pseudonym from your real identity, admitting to someone you know that you control your pseudonym (this work gets lonely, so this is a real temptation), or even accidentally signing off an email with "Thanks, [your real name]". And once you make a single mistake, you can never recover.