I run a small private forum for architects, but would like to add an area accessible to the public, that the architect users can monitor, where laypeople can ask questions or contribute their own perspectives to discussions that are made open to the public.
The idea is that members of the public see only public discussions, while architect users see both private and public discussions.
Members of the public should preferably have a different sign up experience, as there are a lot of custom fields for architect member sign ups that would not be relevant, and should have fewer options from their control panel settings (for example I don’t want to offer the public the same mail-list functionality available to architect members), and public users should not ever be be able to elevate their trust settings in such a way that private area content becomes exposed to them.
I don’t want to create two completely separate forums, as this would presumably trigger the need for two domains, double costs, and add the difficulty of keeping architect user memberships synchronised between forums as they come and go.
How best can I accomplish this?

