How to refinish window rock guard?

Below is the only pic of have of the front of my 1981 Prowler taken in 2007 after I had painted the rock shield probably 3 times over that 26 year period using regular outdoor Rustoleum enamel and sometimes I spray coated a light coat of marine varnish over the enamel to make it last a little longer. IIRC I had to repaint about every 6 or 7 years with the first painting after around 15 years. I simply used a brush and went over the existing design and first sort of lightly sanded the surface. I also had fiberglass strands showing before painting and all that wear I attritubed to wind wear over the years. Note the right side of pic is just from the sun glare when the photo was taken and not from fading/wear.



Larry