I've worked it out! I was given an old Toyota Camry recently, it was a great runner until I made a small error with the water/fuel ratio calculations for my fuel saving "water injection" device that I was almost ready to market internationally. (oh well, the fuel savings would have been offset by the cost of several miles of garden hose per unit...................)
Anyway, I've now found a use for the Toyota, and a device to trip the lights, all in one fell swoop! I've converted the "cowcatcher" device so I can attach my bike to the rear of the Toyota, and I just "push" it with my bike! The weight of the toyota (once rolling) makes light changing a cinch, and now when it rains, I just park, jump off the bike and sit it out inside the car with the radio going, safe and dry. Fantastic!