Garage Vary FRP fiberglass rear panel for NA, how to paint?

[— Malibu Q —]

1. Yes, light scuff, clean and some kind of adhesion promoter. Primer is easiest.
2. Polyester filler (bondo) is best. If they're only small, use the fine fill version.
3. Wait till the first layer has dried fully, polish but don't wax, mask, light scuff, clean, paint.

Also, I did what Willywongka stated, then glued studs onto the back of mine in the outer corners, so I could correctly adjust the fit.