Barry, thanks for the input.
The plate in the pictures I got from Layne had the plate bolted to the bottom horizontal surface of the bumper. Because of the contour of the bumper, it was difficult to get it to fit. Layne made his out of steel.
To protect the lower radiator and other stuff, I would think you would need some pretty stout material. I saw an Aliarc aluminum bumper the other day that had a deer run into it and the bottom skirt was pretty well crumpled.
It sounds like you bent flanges 90 degrees to attach the aluminum plate. ? If so, keep an eye on it for cracks. Thick aluminum needs a pretty generous bend radius to avoid fatigue cracks.
Bob