What would probably be easier would be an easily-activated helmet light. There's not much reason for lighting up anything above waist level unless you're reading street signs or watching for bats (and since you're on a 'bent, you'll be ducking under any low-hanging hazards anyway; upright riders would have knocked them out of the way, too).

A helmet light can point as high as you want, though, like a high beam to complement the "low beam" role of the main light. Then, when you've seen what you needed to see, you can turn it back off.