Hi Jeremy.
In regard your post 'Tor and Namecoin' here... https://lists.torproject.org/pipermail/tor-dev/2016-July/011245.html
In this thread prefixed 'Onioncat and Prop224' started and spanning from here through now... https://lists.torproject.org/pipermail/tor-dev/2016-April/010847.html
Onioncat is interested in finding way to extend IPv6 addressing past prop224 for use by IPv6 native user applications.
There are some purely internal ideas for that. Yet to extent an internal tor+onioncat solution may be difficult, onioncat may need to develop or shell out to a non-native mapping and lookup layer. Namecoin has been mentioned among prebuilt potential solutions.
Note clearly namecoin usage here *not* for human DNS style naming such as myeasyname.onion. But as a mapping between crypto key of onion (descriptor, hsdir, etc) and character string of (in format of) IPv6 address for use in IP / tunnel addressing.
And most certainly any external layer must be capable of having nodes binding natively in the Tor / I2P / etc networks, and preferably being strictly private entirely within them (like how private Tor / I2P / Bitcoin nets can be deployed by generating new authorities, keys, genesis, etc). Outproxy is not an option.
It's also not ideal to be expending resources on mining whereas other form of simpler distributed registry network may suffice onioncat purpose.
Anyhow, fyi as to this thread and any ideas / collab :)