So... my friend in France has organised a "tough mudder" type race for the start of next month. It's near the Gorges du Verdon (translation: it will be in the forest and lakeside). The problem is, it's an overnight race. There will be no ambient light, and it's almost a new moon, so no help there. The runners will be wearing headlights, and guided by glowsticks.
I'm only an amateur photographer, albeit technically minded.
My current gear is:
Canon 6D, 2 batteries
Speedlight 430EX II
Canon 50mm f1.8/II
Canon 70-200mm f4/L
Canon 16-35mm f2.8/L II
I can rent whatever equipment I need, within reason. If it's large, I will have to find a French supplier, as I'm flying, so it should preferably fit in a medium-large suitcase.
So... I really need some advice, both on lighting equipment / lenses and technique. There's some limited reading out there on the internet, but any specific suggestions would be greatly appreciated
My thoughts so far are that I will need some sort of ambient light at the photo point, e.g. a soft floodlight, both for focusing help and for ensuring that I don't surprise or blind the contestants with a flash. Due to the location, they will have to be able to be powered by an on-board power source with sufficient juice for a few hours of shooting. I'm unsure of the focal length needed at the moment, but I know that something f2.8(L) or better would definitely be a good idea.
Please share any expertise you may have on lighting/flash and lenses, and on suitable shooting techniques, as this will definitely be pushing my photography abilities to, or past, the limit.