Top-Flite Monokote comes in a Clear that is treated to accept paint. At least TF USED to advertise it that way. "Clear" is still listed among the available colors.

So, unless there has been some change in recent years, you should be able to airbrush that to your heart's content and probably most paints will work, but if your airplane uses glow fuel you will need to clear coat it with something fuel resistant if your colors are not.

I have used Top Flite Lusterkote clear (comes in spray cans) for this, but a lot of us are less than happy with these cans. On my recent project I was using the Matt Clear over Krylon colors from spray cans. One can of clear worked fine. The second one would occasionally spit big drops of liquid among the fine spray mist that would leave a visible spot after it dried. Interestingly, the Krylon spray cans, that cost half as much as the hobby spray cans, never gave me any trouble.

Tom