I don't think sci-fi and miscellaneous/alternative have to be separate sections.
Perhaps writing set in the future and pre-modern era could be combined?
The idea I still like the most is having things set in the regular Taijitu setting and things set in alternate related or unrelated settings being separate sections as Oz suggested, with modern and pre-modern falling under the former, whether in separate sub-boards or not. Since we date our threads by convention, I'm not sure two separate boards is strictly necessary to distinguish the two.