I think I'm leaning towards this option (even though it will be me who gets the alert at 4am that the server has crashed and is waiting for me to re-enter the key so it can start again..).
The only thing conceptually broken about doing that is that I'm the only one with access to the box, so if someone is able to hack in and gain root access to copy the database, they could equally install a key logger to grab my 4am key entry.