I spray a high end clear coat over all of my paint jobs. I always prime and base my airplanes with rattle cans. Only overnight cure time is nessesary for it to gas off, then you can spray the clear coat. i do all of this in my garage or driveway.PPG also makes a flat clear if your interested in going that route..but i highly suggest clearing your model with a good clear coat. Rattle can primer is not fuel proof and will cause a hell of a time after the exhaust hits it, you will be upset...dont ask me how i know this.
Cole