early start times are one reason for low ridership that I have never thought about. But really, beyond the 200k, I wouldn't want to start late. We have been starting our local 100k rides at 9, which works out okay. I really was happy starting my 200k perm at 6 last weekend, it made the roads a lot nicer with so little traffic.
Randonneuring has really changed my view of getting up early and staying up all night. I am so well adapted to it at this point that I really wonder about some of the research that says it's bad for your health.