I think that's the idea. All connections would be routed via Tor. Additionally, the local system wouldn't know the external IP address (would only know the even

I think that's the idea. All connections would be routed via Tor. Additionally, the local system wouldn't know the external IP address (would only know the eventual Tor exiting IP address.) It's possible to virtualize Tor (without running a dedicated router) so that it, too, doesn't know the external IP address. You can do this, as an example, in FreeBSD jails, and instruct the firewall to NAT all connections from/to the jail in which Tor is running. Of course, having a dedicated hardware router running Tor is even safer.