Tom,
One thought for you, running DC power, you mentioned you run at low speed. Might you consider using LEDs ? The strip LEDs that most of us use are set to operate at 12 volts, you might assemble your own LED lighting using individual LEDs with a buck converter adjusted to limit the output to around 3 volts. I would still use the rectifier in the circuit, if you do reverse the polarity the cars will light in both directions.
Ray