When I ride double centuries I usually start in the dark and end in the dark. On the Cameno Real Double in Feb. we had an hour and a half in the morning (5:30 AM start), and two and a half in the evening (7:30PM finish), i.e. before the change to daylight savings time.
I enjoy riding in the dark as long as I know the course and don't have to stop and look at a lot of street signs along the way. I use a NiteRider Blowtorch for a front light, and have two Planet Bike Blinkies for the rear (one on my bike, one on my Camelback).
So far, no issues with cars, and the NiteRider lights up the potholes quite well, so no issues there either. Night riding is fun and esp. so on otherwise empty country roads.
Rick / OCRR