Before digital cameras with adjustable diopter viewfinders I used to keep my eyeglasses scratched up pressing my glasses and eye against the camera viewfinder. I learned a trick that worked very well on plastic eyeglass lens, I think it will work here. I would find a container that the glasses would fit in face down and pour in about 1/4" of Future floor wax. Dip the face of the glasses in the wax and gentally lift the glasses out and with the sides open just sit them on a paper towel and let the liquid wax sheet off and dry on the lens. WaLa no more scratches. Eventually the wax would get new scratches and I would use household ammonia to remove the old wax, rinse in water , dry, then reapply the wax.
I would if possible disassemble the truck, wash the roof in dish detergent with a SOFT brush to get any paint dust out of the scratches, rinse, dry , let set for an hour so any water in the bottom of the scratches dries. It must be totally dry, set the roof in the acrylic floor wax. As you remove from the wax tilt it a little to one side and let it sheet off to the side. Hold it at that angle with a paper towel catching any runoff. Once dry the scratches should just about be invisible. You can recoat if necessary. If it does not work household ammonia will remove the wax. You should be able to keep the wax off everywhere but the roof with just a little care. Acrylic floor wax comes in high and low sheen I think you need high sheen. j
