There is no real way to import backuped host configs. Best would be to boot from time to time into a tool like clonezilla and do a blocklevel backup of the complete boot/root drive. If something fails you could then boot again into clonezilla and restore the complete drive from a backup.
If you can't shutdown the server and manually boot into clonezilla that often you could also use something like rsync or the proxmox-backup-client to create a backup of the mountpoint "/etc/pve" where all the PVE config files are stored.
They are also working on host backup capabilities for PBS but that isn't ready yet.