The only thing about flat black is that you can't sand and buff it. And when any paint gets sprayed, there will be some dirt that gets into the paint and they might even get a run depending if they can spray worth a ****. If you spayed a regular gloss all the dirt and runs get sanded and buffed out. But since you spray it flat its gotta stay. Thats something to think about.

The way I would spray it so that it would stand up to the wheather is spray the black base and then put a flattening agent in the clear coat and it will go on shinny but dry flat. That way it will still last for YEARS in the wheather!

GO FOR IT! I LIKE THE IDEA!