How can I ensure that I can always have Hyper-V Manager access to a Hyper-V server, even in the event that the Active Directory Server is down (in a domain-login environment)?

Background: 

The person who managed infrastructure before me set up the company's servers as virtual machines on top of a host running Hyper-V Server 6.1 (7601) Service Pack 1.

To manage Hyper-V, he installed Windows 7 onto a virtual machine (run on the same host) with Hyper-V Manager installed.

When the (virtual) Active Directory server (run on this same host) is rebooted, during that reboot, I'm unable to RDP into the Windows 7 virtual machine, and I'm therefore unable to access Hyper-V Manager when the Active Directory server is down. I suspect I can't login because I can't authenticate with the Active Directory Server.

I'm going to install Hyper-V Manger onto some addition manager's workstations, but how can I ensure they'll have access in a catastrophe where Active Directory authentication isn't possible?