At the moment I'm looking for an oblong type light, like a small light bar, with a rear fitting bolt that would be larger than the gap between the horizontal slats on the front, level with the headlights, that I could bolt into a vertical aluminium bar behind the same slats. That should hold it firm, but there would have to be some adjustment up/down to adjust correctly. This way there would be no drilling. Just have to keep looking.
Wiring would use a relay with fused input from the battery. The relay would be switched using a switched feed from the side/parking light.