Actually I have done some airbrushing on my hull and the engine as well. And I used PPG automotive type catalyzed paints in a base coat, airbrushed graphics and then clear top coats to protect the finish. So it can be done. It just comes down to what you want to do. Once you do the clear coats, the finish is impervious to oils, fuels and such. If you don't use catalyzed paints, they will dissolve over time with oils and/or fuels getting on it.
If you care to see how I did that, click on the links below for the engine and actual boat thread and see. Nothing great, but I did use paint instead of decals so they won't peel off down the road. JMHO