@Matt_Noyes @Antanicus @vmatekole @mattcropp
IMO it would makes sense to start by using the invite system introduced in Mastodon 2.1.
To explain, unfortunately the cron script I had written to auto-create Mastodon accounts wasn't simple to port to our new containerised Docker Swarm based setup. @vmatekole has a script or method to manually create the accounts in the meantime (I added an API to our membership system to help with that) but I have no info about how to run it.