Sub forums and you get up to three tags. I'd go with one hash tag myself. Because right now, like you've said, this is a mess. There's a widely used and perfected forum template for a reason. Some of these solutions are needlessly convoluted. Is the forum really better if we have to check boxes and categories with hash tags some of which are prioritized and some of which aren't? All that does is turn people off to discussing here. It's gotta be quick and easy like the widely used forum template is.