[Squawk 8888]

there are some companies that market a small device to motorcyclists which is mounted on the underside and hangs down closer to the road than the bottom of the engine (it appears to me to be a poerful magnet)

Your instincts are correct, it's just a magnet. You can spend $20-30 on the "signal activator" or you can just go to the hardware store and get a large heavy-duty magnet for <$5.

[WayneS]

Or, you can do what I do on my motorcycles.

Wait through one whole light cycle (two if I’m feeling extra “cautious” that day) just to verify that the light has, in fact, NOT been “tripped”, and then run through it at the first safe opportunity.

Later. I DO go ahead and call VDOT and report the light. They seem to actually make an effort to recalibrate the ones I report.