I am running a 400km called the "Avalon Sunrise".
The concept of the ride is that you start at 10:30 and see the sunrise somewhere around Glastonbury
It runs on the weekend nearest midsummer, and with that start time and that date, the sun comes up for the typical rider somewhere near Glastonbury
If the date moves, so does the sunrise. So the nearer I can get it to midsummer, the better
I don't think I will get lots of late entries from PBP hopefuls who failed on their first 400, because two 600 is as easy as a 400+600