Group/hide optional fields in the New Topic menu?

I am currently using tags, together with Location and Event plugins in most of the categories of my Discourse instance, since almost each one may need them. The problem is: when you create a new topic, a lot of informations are needed (subject, category, tag, date, location), which is discouraging for new users to create new topics.

It would be convenient to be able to group all these optional fields under a More fields… button, or something similar. Is it possible?