Need your help and expertise

We are designing a Veeam B&R + Veeam agent backup solution for a big customer:
- Veeam Backup for Hyper-V
- Veeam Backup for a standalone ESXi
- Veeam Agent Backup for physical Windows Server (Hyper-V and AD) and Linux
This customer is very very "security sensitive" and doesn't understand/ acept why Veeam B&R needs local administrator account permission to manage backup of physical server or Hyper-V VM or Hyper-V system (C:\).
He used HP DP and told me that HP backup agent only needs backup operator permission do do the backup ...

Before sending this post l i've read several docs, one big one for vCenter permission (https://www.veeam.com/veeam_backup_9_0_ ... ons_pg.pdf), but vcenter centrix only.
So, Is there any whitepaper or Best Practise or trick to fine tune Windows/Linux account used to backup physical Windows/Linux or HV server with minimal permission ?
Thnks a lot.
Sebstien