Take Offline

The hard party might be getting approval for a second license to install inside the VM but it would give you a simple way to run your custom apps on top of the stock image. Then you just have to keep your own backup of the VM and manually install the VM app in the event of a host OS re-image.

Not sure if it'd work for you but it may help if your rebuilding that often. Especially with restore points for the VM if it's your extra apps that cause the issue.