Regarding using a headlight, either frontwards or backwards, in the open bike class at BUB, M class or A class, no streamlining is permitted. The rule reads as follows: "Streamlining is anything that has the perceptible purpose of directing, controlling or limiting the airflow around the motorcycle and/or rider, or is placed to reduce aerodynamic drag." I would interpret this to mean that a headlight would not be permitted, as it could be perceived as partial streamlining. Don't give the inspectors pause for concern; you need them to be your friends!
Tom