I'm not going to requote the entire thing, but this is great. Exactly the kind of input I was hoping to get. Yes, mandatory access controls and firewall rules are other forms of isolation that I didn't mention. I was too narrowly focused on VMs. Theory meets practice at some point. Since posting this guide, people have admitted to me that running Qubes or setting up an anon middle box (even following the instructions to manually set up the Whonix Gateway on a separate device) is beyond their capabilities. A big difference between Xen and VirtualBox is that there is a preconfigured solution for VirtualBox, and that's better than no virtual isolation at all. What do you mean by virtual air-gapped? This really needs to be TODO item #1, like out in the next version of Tails.