I've got an older Cygolite that I've used for commuting and longer brevets, with a helmet mount. My dyno lights are fine for most rural riding, and I can turn it on steady or flashing to see street signs coming up to a turn or in towns. I mention Cygolite because they'll sell you a spare battery (or two) to get you through a second (or third) night.
If you're sure you can get a full charge at each overnight, I suspect most any modern light will do. Just run it on low power, or shut it off until you need it.