If they are based on inductance, which does seem to be the case, wouldn't a small magnet on the bottom of a bike increase the inductive disruption, thereby increasing the chance that the signal will detect it? Some of the articles claim a magnet doesn't help, but they might just mean that it isn't magnetically based.

Luckily, most of the lights I have to worry about are camera triggered, and my lights set them off just fine.