A few weeks ago I had some new truck signs made. There are three of them digitally printed on .060 aluminum. One will be mounted on the tailgate and the other two are going on the sides of the bed toward the front. This is the first set of signs that I have purchased made this way. My other graphics are vinyl applied directly to the truck body. Question is, should I use some type of backing material to support the aluminum or can I simply pop rivet the aluminum to the frame of the bed. What do you guys think?