You've got the right idea Ed. Anywhere a decal or paint is applied should be black in the Blue channel or else the metalic will come through. Also, here's a little tip: I used to make all my decals, lettering slightly more matte in the green channel by copying them over and making them slightly lighter grey. It was just a lot of unnecessary work because, from observing photos of real planes, I found there is in actuality a clear coat spray over the entire finish once the paint has been applied. The gloss on the decals and paint therefore are all the same as the fuselage. The exception might be warbirds where paint was applied with a brush in the field, like DDay stripes. Those may not have the same roughness as the fuselage but slightly more matte as paint would have been applied over the factory clear coat. It really will depend on the aircraft you're painting, the era, and the markings to decide if you should affect the gloss of the applied markings.