Maybe back on core topic this year's big investment with Le Mans in mind is a wood fired USB charger.
http://biolitestove.com/campstove/ca...view/features/
Really hoping it works a lot better than last year's complete failure with a solar panel and what has, in the past, ended up with an awful lot of juggling stuff in the car to get a modicum of charging done. Also figure we might be able to amortise purchase price if we rent it out a little while it's being used for boiling the kettle...