i always have a front LED blinkie i run for front vis, but road illumination on tour is more of an emergency or occasional thing, certainly NOT worth packing a road light HID thing and charger, unless you were specifically a night tourer.

I did bring my Nightrider HID light last weekend on tour to ride a 2 1/2 mile converted rail tunnel (longest tunnel open to bikes in the United States!)

i get fourteen hours from one battery in a petzl climbers' headlamp that throws a 100M beam i bring in the winter on tours, and always a smaller but still powerful Black diamond climbers LED headlamp that is more than adequate to limp along at night. And the AA batteries in that last 200 hours or some ridiculous amount like that.

A Busch and Muller bottle system or a Schmidt dynohub would make sense for global touring.

Full moon riding without a road light, nothing quite like it....