The one glaring issue, is that I also want to keep a backup off site. Ill look into those two options, but to keep it automated and to use CCC, I would have to unmount all the CCC backup drives. Shutoff the mac server.
Well, depends what you mean here. Surely, you need to unmount the drive from the server which serves the partitions... But that is single piece of hardware and you need not to shut it off, just unmount the drive. And that can be done by script automatically at appropriate time or manually very easily.
But you do not need to dismount each partition from each client individually. CCC is smart - it WILL automount the target (and source also) drive when needed (if it is available) and it can dismount the drive when done with copying - simply select it as what to do after it is finished. I do that, so the CCC target disks are actually mounted ONLY when CCC is doing its scheduled backups. Users cannot accidentally write stuff to CCC drive this way.
Here is reasonable sequence of rotating two external (USB) disks - disk 1 and disk 2:
Server has Disk 1 mounted, and backups on clients run overnight... In the morning, unmount Disk 1 from server (or have it unmounted by script) and take Disk 1 with you.
Connect Disk 2 to server, it will auto mount to server - but clients will find it on their own ONLY when they are scheduled to do backups, mount each their own partition, do backup, unmount. By the morning all backups are done and partitions unmounted from each individual client. Unmount Disk 2 from server manually or by script, Take Disk 2 with you, attach Disk 1 and all is ready to repeat as needed. Switch between Disk 1 and Disk 2 on schedule you need.
Check CCC help for this. This really can be very easy and transparent for user.