What would be the easiest and best way to ground license plate lights when attached to diamond plating?

My vehicle doesn't currently have a bumper to hold the license plate lights. I have the lights attached to diamond plating with Quick Steel and I need to know how to ground the lights so they work properly.|||you will have to run a ground wire to the frame or if the plating is bolted to the frame member/ then run a ground to the plateing. use a self drilling bolt to a clean ground to attach the wire and cover with liquid neopreme to seal