I am planning to host my forum invite-only, so no randoms or bots will be able to post stuff. Additionally, if it picks up activity, I hope some of my friends would also help with moderation.
I agree. That matches my experience so far. Just so many things one might need for a forum have already been covered by Django. The ORM is easy to use, mostly and select_related and prefetch_related help with avoiding unnecessary queries, which can quickly arise in a forum. For example simply when listing threads, you might want to know an excerpt of the latest post in each thread. But also the way one names url patterns and then refers to them in templates, so that changing the url patterns (except for changing the name) does break the templates. Or the way Django forms make building forms not much work. In summary, so far it has been a delight to build it using Django.