I think they best setup would be to get a low amp alternator (these can be custom ordered for place theat sell high amp alternators for audio system). A race battery will save around 25 lbs too.
This is a race type setup and would be very efficient, But It wouldn't work good in the winter. And I would be very nerous with this setup (i don't know if it would work in a rain storm with the high beams on). Gains would be minimal.
^
this who post is sorta off topic from the original post...
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2008 EPA adjusted:

Distance traveled by bicycle in 2007= 1,830ish miles
Average commute speed=25mph (yes, that's in a car)