My current project is developing VR physiotherapy for disabled children using the Vive and its puck trackers. In this case the therapist needs to be able to control the experience of the user in VR at the monitor, but also to be able to see the VR view. If you've played The Lab and seen the Level Select menu overlayed onto the VR view on the monitor, that's pretty much exactly what I'm going for.
I have a second camera with a seperate view from the VR view working fine on the monitor...
Menu to control VR game on monitor that's not visible to player in VR