You could do this with MySQL Master/Slave and RSYNC
Have RSYNC run through Cron every 12-24 hours to copy over the necessary moodledata files and skips all the other un-needed items. Doesn't really need to be 24 hours.
Setup basic auth with LDAP in apache to control who can access the server, i.e// Faculty/Staff OUs so that nothing in Moodle (Roles/Permissions) needs to be changed and keeps students from logging in.
In case of failure, switch MySQL to master and remove the basic auth from apache. Change DNS or use a load balancer in Active/Standby so you don't have to mess with DNS or URL issues in Moodle.
JASON