Robin: indeed an interesting proposal. I don’t have such a filter but others doubtless do. They are hereby challenged to try it!
I also thought of using a video camera, subtracting a constant level from each frame (the minimum value contained in the frame might work) and then co-adding a goodly number of frames. Again, a constant level would be removed from the final stack.
The sky, being a noisy constant, would be smoothed and reduced markedly but the (again noisy) signal from the stars would be increased relative to the background.
This, of course, is essentially what I do to image extragalactic GCs, TNOs, and satellites in the outer solar system, some of which are markedly fainter than the sky behind them, though rarely are more than a couple of hundred subs stacked.