You could also set using spacers which then could be removed later. They were there to hold things down, again as stated above appearance was not a concern thus the rivets were painted and never covered when cars went to get sprayed. Function over looks.............
Its like the front spats on my car, rivets were exposed as it was an add on later down the road. My painter had trouble grasping that idea as they are a bit hobby shop which is exactly what these things were in the day.
This is how close original cars skins were to the frame, would make for little trouble......
