General Backup and RAID Qs

Setup:
MacMini 2020 i7 32GB OWC RAM Catalina 10.15.5
Two Thunderbay 4s, each with four 8TB drives each

I have setup the first Thunderbay 4 with four 8TB drives. I created two RAID 5 volumes across all four drives, one 4TB volume that I use as a time machine backup space for multiple other computers, and then one 20TB volume that I use to store all my files.

Now I have just certified all four 8TB drives in the second Thunderbay 4 and I am ready to set it up.

My goal is to use the second Thunderbay 4 to backup the first Thunderbay 4. I am also using Backblaze as my offsite backup (not sure if that is relevant). I have Carbon Copy Cloner and was planning on using it to perform the backups.

Is using CCC the best way to back up my files? Is there another way to make a mirror of the first Thunderbay 4 onto the second one that doesn't rely on CCC?

I don't feel like I need to make extra backups of the Time Machine Volume. I don't tend to store critical files on internal drives of the computers that I am backing up, so the Time Machine Backups are really just worst case scenario if I need to roll back or something. They should be uploading to Backblaze anyway so I really don't see the need for more backup of the Time Machine backups.

So that leads me to how should I set up the new Thunderbay 4 with four 8TB drives? Is one 24TB volume to backup files with Carbon Copy Cloner my best route? I would skip the Time Machine volume on the first Thunderbay 4, so I would have about 4TB extra on the backup Thunderbay 4. If I store anything on that extra 4TB it is not backed up locally. I guess I could always back up both of the Thunderbay 4s to Backblaze, and then I would have a backup of the extra 4TB on the second Thunderbay 4.

Or should I setup the second Thunderbay 4 just like the first one (one 20TB volume, and one 4TB volume) and have Carbon Copy Cloner just backup everything, including the 4TB Time Machine volume on the fist Thunderbay 4.

Really I think all of that is a very long winded way to ask, is there a better way to create a 1 for 1 backup copy of Thunderbay 1 onto Thunderbay 2 than using Carbon Copy Cloner? And does it make sense to make the volumes the same on the second Thunerbay 4 as I have already set up on first Thunderbay 4?