Keith,

Yep, you got it right. I only rough up the white gel coat with 400 to 600 grit sand paper. Then I spray a very light primer. Only enough to look for areas needing filler or touch up. Then I sam much of it off with 600 grit. I use the 3M blue fine line vinyl tape. Yes I butt some of the colors up to each other (red to white and canopy pink to metallic silver. When you lift the tape when the paint is tacking, you get a blended paint line. If you wait until the paint is dry, then you get a sharp line. If you minimize paint over paint, you can keep the weight down. Tomorrow morning, I'll weigh everything for paint and monokote weight. Only my small yellow, metallic blue and maroon was painted over the white. Here I use the 1/8" tape to make sure the color lines are parallel to each other as these colors do not butt up to each other. On the bottom side of the paint, I use the 1/4" tape. This serves as my paint distance guide. This way my side stripes end with 1/8" spacing and exactly 1/4" wide trim colors. Hope I didn't confuse you.

The PPG paint is the same that Tony Stillman sells at Radio South. I believe it is the DCC.