In phpbb we gave loyal members a special private unique rank. They could pick what ever they wanted or could dream up , those ranks where unique. Adding that special rank for a member meant their standard rank was not visible anymore.
No, it doesn't. Set all permissions to no for this usergroup, except the one for the user title, then assign that usergroup as secondary usergroup. What's there to monitor?
The system I pointed you at is not about user ranks, but user title. What you want can be done with custom user titles with minimum work, while it's not easy with user ranks. So why not do it with user title?