Xenon Reverse lights that can be controlled from a switch inside the cabin. If this is not a frequent happening, just slow down to a complete stop, or look as though your going to. People s*** themselves. I use this, but for the opposite reason, when someone does not want to move out of the way in the left lane of a motorway (does not apply to your case, this is not justifiable on a single lane) just pass them on the right, pull up in front of them and start slowing down. They are in the slow lane instantly
But I do this in a matte black Techart Cayenne, so they're also afraid of whose behind the wheel
One of the benefits of having black 4X4s.