In the city where my office is located, I have seen the traffic light technician adjust the sensitivity using a bicycle rim mounted on a board. Most of the cities around here have a white X or bicycle symbol painted on the loops to indicate where to position your wheel.
For the camera based lights, shining my light at the camera always works. I've also "made myself large" by standing tall, waving my arms and/or opening my coat. Drivers think you are looney but so what.