Don't use etch primer on fiberglass.
For less orange peel and better atomization you can do three things: bump your air pressure up, cut the fluid adjustment down-less trigger pull, and reduce your paint more. Make sure you're using the proper temperature reducers and hardeners-if they are too fast you won't get any flow, slower drying products are better for more flow and better gloss retention and they actually reach full cure faster. Get that gun dialed in better before you shoot the car-spray a few test panels first if needed. The fluid to air ratio is key for good atomization and once the settings are dialed in you'll need to apply it at a rate that delivers a slick wet but thin coat-watch the wetness in the reflection off your lights to tailor your application speed.