Vulnerability Scanning non-linked sites

Hey everyone,

So I am in charge of a vulnerability scanning program on some locations that are not part of our Site-to-Site or MPLS connectivity. These sites are completely isolated and need to be scanned.

I am thinking of using OpenVAS and CentOS 7 to create a .OVA that I could deploy to each sysadmin. My question is, how can I remotely connect to the web interface to configure the scan? Could I script some VPN to phone back home to a publicly routable connection where I can then access the console?

Correct me if I'm wrong, but some security consultants have to do something similar with client engagements, right? So if I can do what they are doing, that will allow me to run scans without an active connection to the site.

Thanks!