That separate single WordPress instance doesn’t need to be online, and can be hosted locally. So I installed it on my laptop. That way there is no attack surface for the outside that would risk allowing access to my 6+ sites that run WordPress.
It turns out, an added benefit is that I can also post to any of those sites from this local instance. This has as an advantage that I can draft postings offline on my laptop, and then push them to a website when done. That should help me write more and with a lower threshold. It has a few drawbacks, as offline I don’t have access to some features I use regularly (post kinds, and more importantly previews).
This post serves as a test, posting from my wordpress instance on localhost.