I'd say re-check your wiring and stick with a generator lamp; but I'm a dynolight freak. If you're running fenders, you can get a B&M Seculite Plus for $35. It mounts to the fender, and you can use reflective tape to secure the wiring up the length of the fender before getting it to the frame where you zip-tie it.
If you're having slippage issues with the generator in the rain, consider replacing your rubber contact wheel with a wire brush. I think they have them at Harris or Peter White for around $5.00 each.