[Unkechaug]

This is a bad take. You are asking for the forum and sub forum/tag approach. A community that small will simply not be engaged with frequently enough to avoid seeming “abandoned”. This is exactly the set of circumstances that led to content aggregation sites like Reddit.

[ItsMonkk]

Sub-forums are a usability nightmare, but reddit already solved the sub-forum issue. You would be showed content in a flattened manner, but in the hierarchy where the closest to you is shown first.