Most bike lights do not have a good beam pattern with a sharp upper cutoff to avoid blinding oncoming traffic. I wonder if you could attach an opaque shield extending out over the front of the light that would block the light from hitting the eyes of other cyclists once they get close to you and are above the level of the light.

It shouldn't have any effect on lighting up objects that are at or below the level of the light and would still make you very visible to car drivers from a distance. But it would cut way down on the brightness seen by nearby approaching cyclists.