I would never even consider making a left turn on red, no matter what the law said. The cop that gives you the ticket can always say you did not wait long enough. If the light does not change, I will make a right turn and double back. It's not just the ticket you have to pay. Your insurance will go up for 3 years and cost you hundreds of $$$.
Those magnets that are supposed to trip red lights simply do not work, even though some people claim they do. I work for a city government, and talked to the traffic engineer about it. Most of the time a bike will not trip a brand new grid. After a few months of wear, after about half the wires are broken, even a small car may not trip it. They do not have sensitivity adjustments. They are designed to be as sensitive as possible, but they are designed for cars. My city is slowly replacing those things with sensors up on the signal light arm that are sensitive enough to pick up a motorcycle or scooter. Some lights are on a timer and change anyway.