Would it help if the VR headset allowed for some Actual Reality to seep through in some controlled way? Couple of ideas come to mind --
1. Have a faint overlay of "AR" with the VR image. Could be that the physical screen is partly transparent somehow so you can see the outside, with a controllable (manual or automatic) transparency.
2. Have a small square patch of AR in your field of view, say in the upper right corner, that your eyes can dart back to when your brain needs some grounding. Kind of like a little plug in the headset that when you remove physically with your hands, you see a hole through which the real world shines through. When it's plugged back, you see a black square in its place. Actually it would be more like a camera shutter -- touch the headset on the side and it opens/closes.
3. Time-shared -- at certain times, auto-deduced or manual, the entire VR quickly fades in into your entire field of view. That would be best if optical and not rendered, so it may be a form of (1) -- unless rendered is fast enough (maybe with direct circuitry from the headset camera to the screen, without going through the PC).
The idea is the very moment you feel uncomfortable you touch the headset (perhaps even command it via EEG) and you see the real world immediately -- without worrying about taking off the headset.