There are three metal strips embedded in the plastic, but no provision is made for termination to the light or to external leads that would jump to the gen. I'd have to carve off a lot of plastic, with the risk of finding metal that is hard to solder or just plain fragile.

I just took off the fender. I'm gonna give the inside a good wash, drill access holes, mark the gluing area, and prepare to install a pair of wires using RTV.

Wife's Breezer seems to have turned-in lips which can be used as conduits for taillight wires. Not so the Zefals!