The skirt does not lay flush against the steel frame in a number of places. Riveting these areas will force the skirt to conform but you will get some deformity in the surface of the skirt which can be noticed after paint. I decided to purchase some small nylon washers in varying thicknesses and use them to fill any gaps between the skirt and frame. Once I decided on the appropriate thicknesses I epoxied them to the skirt. The thickest washers were only 1/8" while some were 1/16" and others 3/32". They won't be noticed once the skirt is painted and riveted.
