Nope, a rear-facing driving light just needs a red glass lens.
Susquehanna MotorSports - Detail
And now that we are way off-topic, I do like these: 1156-PCB-R36 Red LED lamp
Product Listing - CAR
So I could keep my tail lenses stock. $9.95 apiece for 36 LEDs
Any word on the price of the ones used to do this mod?