I'm doing a modifie version fo the northern tier and will be having longer days than I normally do and have come to grips that I my run into a situation where i need a light. I've often carried a cheap cateye halogen for tunnels and worst worst case secnario, but ahve never used it for anything but a long tunnel. I do have a tail light. However, I think if I were actually forced to ride at night, i'd want somethinga bit better.
Money is only a factor in that thats money I could use for something else. This is not something i plan to or want to use and would only be used to getting to the next campsite (so battery life over an hour or so shouldn't be needed). I will have a handlebar bag so I can't bar mount, but i'd be willing to rig something to the front rack. I'm not adverse to helmet bags. However, I'd like to see and be seen.
Any advice? What do others use?