Can you set it to prevent new logins after the grace period starts?
Also is the auto process doing full backups in case stuff goes wrong?
I do not know of any way to stop new logins from happening, sadly.
As for full back ups, it does backups of the world, players and config files, but none of the game or mod data (I dont have the space to back all that up). If any of the game or mod data gets corrupted/broken we are screwed anyway until devs fix it.