Have you tried using a policy to install the auto login user account at the enrollment check or regular checkin? I have a policy that scopes via smart group. The smart group looks at the the systems i expect to have an auto-login account, and if it does not exist scopes my policy to them.
This policy can be run at checkin or via self service. It installs the .pkg, runs the iCloud Suppression script and restarts the system. When an instructor finds a laptop that isn't auto logging in anymore, there is a self service policy to delete the auto login account. Than either re-add it via self service or the instructor can just walk away and let the system re-add the account.

Be aware of the caveat with createuserpkg that you can run the risk of creating two accounts with the same user id number. If these are only going to be used with this auto login account you should be fine. But if you need to set up a bunch of other accounts for users to log out of the auto login and log in under they're own id. The better method would be using Casper to create the account and drop the kcpassword file in with a .dmg than restart.

@blindcola thanks for the reply! My idea was just a bad idea, so I'm scrapping this one!