How about fitting a hub dynamo front hub, and an LED headlight?

Schmidt, hub Dynamo and dual headlights is just the thing for Paris- Brest- Paris.
where the ride is starting and finishing at night.

and no battery light can put out that level of light for that many hours.


go cheaper , Shimano or other hub dynamo and all sorts of wired headlights.

Planet Bike has a wired handlebar mounted light,
you can unplug it from the hub and remove it from the handle bar ..
you have no battery life concerns then, and as dynamo, laced in the wheel,
works in all weather..

P-B also has Battery LED lights , I have a 1W version, they make a 2w too.
they are multimode blinky aka superflash. , fairly spot beam.

Nice German made imports too, Busch and Muller, AXA Basta, Spanninga, etc,
they are not multimode as German law requires
lights to be steady on,like all other vehicles.