For some odd reason, I can't help but think Craig's got some suggestions on this...
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You can grab something like a minimag that would accept a madmax/badboy LS module. Then you can supply the minimag with a RAM clickie (red clickie) that's really soft on depression and can easily be turned on with a tongue push, of all else (the spring's almost too soft)...
LSs are pretty bright for its size, and can easily outwhip any 2AA incandescent ligth in terms of output, and in some cases, even throw.. For drop-in pills that are readily available, I find the BadBoy 400 w/ Q3L upgrade to be the brightest overall, with the MadMax+ Q3 the brightest initially.
You'll want a high dome with an NX05 collimator for a good throwing light. For a smoother beam (IMHO, a more useful beam for trekin' in the dark), you can choose either a McFlood reflector or a low dome LS with an NX05...
Just a thought...