That's exactly what I did to my rocker moldings. They're also finned. Sprayed, then wiped the paint off the tops of the fins about halfway through the cure process.
Clifftt, I recently got my rocker moldings back from being polished at Auto & Truck Bumpers in Hayward and they need to be painted. A while back I bought theses stickers from Layson's to apply to the rectangles on the rockers. I 'm a bit concerned about how well they would hold up and the difficulty of getting them on straight. I like your idea better.