After playing around for a bit, this really looks like the best option. I will wait until federation support gets added to the self-hosted version though.
2 days ago from a contributor on the Ghost GitHub Issuetracker:
ActivityPub is currently not supported for self hosted setups, we're working on getting everything working smoothly internally first before adding official support for self hosted setups!
I should clarify, I suppose. "Available" as in you can go into the settings and turn it on. I assumed there was something wrong with my personal install when it didn't work but I guess it's just not finished yet. Sorry about that.