Hi
How did you get Proxmox to use ISO and Backup? Tried many times under NFS would not have it, in my case it came down to the fact that Hetzner who I rent my server that has Proxmox VE on requires port 111 for NFS to be open. German law say's no because they do not want "portmapper" running. As far as Proxmox auto folder is concerned you will have major problems trying to disable it, mainly because it is hard coded.
Version 6 was better.