It might be easier to design the room to create false positives and undermine trust in the detectors. Assuming you have that kind of influence, anyway. That's not an option if you're just trying to plant a camera in an existing room.

I assume minimizing the aperture would be a fairly reliable way to avoid detection. A pinhole camera would be hard to find by any optical technique, though the video quality would suffer. Perhaps one could project through a pinhole onto a screen and record the projection, so the sensor is angled away from the room?