I found these articles on Choosing Your Desktop Linux Distribution and Desktop Linux Hardening to both be interesting. At the bottom, you’ll see that they recommend using Whonix. Pretty clear Whonix is designed to be used within VirtualBox.

When I tried installing straight to Virtualbox using the Virtualbox instructions, it took about five minutes on my (admittedly old) machine. Then, I got a driver was not set-up correctly error. It tells you what to do:

$ sudo modprobe vboxdrv

After doing this command, the virtual machines booted normally. Unfortunately, I could not get them to work, probably because I use a very old notebook.

Anyway, adding a comment here as a note to revisit once I have a box that can handle the virtualization requirements.