My panel is primed, and rattle can gray enamel that I found to almost match my interior.
After that I just shot standard clear over. To my knowledge, clear will stick to anything except water base paints. Iíve never had an issue. Might try a small sample first. My finish is a gloss though. Havenít tried a semi-gloss clear.
Other projects though a so I gloss poly out of a can has worked well.
Fuselage-?? Working on it!