there already exists a working DNS system for TOR which is based on Namecoin technology. It's called 611 and is an open source project on GitHub:
If you like it you can join the discussion on:
Registered domain objects are reachable under the anonymous domain YOURNAME.611.to, like
Using the Qt "611 - Wallet" it's very easy and intuitive to manage your domain name objects
Screenshots with short description of the additional wallet features are available on this website: https://flo.sh/611-sixeleven/
Moreover 611 already offers additional TOR services. You can use it to publish an onion website for both: TOR and non-TOR users by using a free service.
The websites examples above i.e. are also reachable for non-TOR users using a Tor2Web proxy.
TOR users should be automatically redirected to the matching onion website.
As the whole project is blockchain based on Bitcoin technology you can always check the validity of the published information using an extended Blockchain Explorer at https://be.611.to
Let me know if there is anything missing for you :)
More information about formatting options
Drupal Design and Maintenance by New Eon Media
Drupal Development by Chapter Three