Not an expert but I use a 3-server, 9-disk proxmox/ceph cluster. I back this to PBS1 which syncs to PBS2 (offsite). So all VMs and CTs are covered.
But what about yourProxmox servers with all the PVE/Ceph/Certs?
I think one good answer which might stay true to "The Proxmox Way" is be to...