My license plate is supposed to be mounted underneath the left light, which has a special provision for illuminating the license plate. That would place the plate very low with very low clearance. That means that if I, say, back over a curb or some such, I would not damage the lights, but I would damage the license plate. So, I decided to hang it on something flexible so that it would flex away rather than bend or break.
After looking around, etc, I decided to buy "EPDM rubber sheet" from McMaster. That's black, 3/16" thick rubber. It possesses some very amazing properties -- it is clean, does not mar, it is very soft and flexible and yet very tough. I will hang my license plate on two 2x4 inch pieces of this rubber, I would bolt the rubber both to the truck bracket as well as to the license plate.
This material is highly recommended. I paid about $9 for a 12x12 sheet, and so far used only 16 square inches from 144 square inches total. I am sure that I will find more uses for this wonderful material over the years.
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