German lights, like the asymmetric B&M lights, do have a fairly sharp cut-off. I understand Cateye used to make lights with this asymmetry. To be honest, I don't think it's feasible to make your own lenses or reflectors, because of the rather precise shaping that would be involved.

Perhaps you might mount your lights up at the fork crown. It's a compromise between your desired ultra-low mounting position and bar mounts. That would allow you to angle the light down a bit, reducing glare to oncoming traffic, while still giving you some parallax between the light and your eyes, allowing you to see part of the shadows from potholes or road debris.