I have a Ryzen 7 3700X - which seems to say it supports SEV:
flags : ..... sev sev_es
$ cat /run/qemu-server/host-hw-capabilities.json
{ "amd-sev": { "cbitpos": 47, "reduced-phys-bits": 5, "sev-support": true, "sev-support-es"...
If you're gunna be running Proxmox on 48 nodes, use your commercial support to lodge a ticket to get exact advice on your setup.
You do have a support subscription given that Proxmox VE is core to your operation, right?