Maybe this is the time to get creative and hand-sketch some ideas out on paper ...use yer imagination to see what you 'could' do, what are extreme ideas and conservitive ideas, projector lights(??) ..how 'cool' could you make something (like a brain-storming session). I used to hang with a crowd who used to do street rods. We used to fabricate a lot of fun things out of steel and/or fiberglass. It's not that hard to make fiberglass molds out of foam. Be nice if you had your old one. Like they said, go back and look for it. Even pieces. You should check out some videos on youtube about making plastic or fiberglass molds. Your imagination and ambition is the limit.
If yer not sure what to do and want to take some time, just put some chrome stove bolts (with hex key), or painted body color, etc .. and put in until you decide. Then you still have the mounts in place if you decide you want to do something ...or find a replacement panel. It's actually kind of nice to have the mounting rivet bolt holes in place for a future mod. If you grind them out, then you have to deal with the holes. And the only 'good' long-term way to deal with a hole in steel is to either put a bolt in place, or fill with weld and repaint. And welding flat sheet steel on a roof takes finness (so ya don't warp the roof). If you bondo or fiberglass over the holes, it'll work short-term but they'll reappear.