...if the rubber washer around the bolt were black and fit correctly while the bolt was a hex bolt, then i think it wouldn't look too bad.

mayonaise: the coupe and sedan have different sized rear-windows to my knowledge. you would probably want to purchase a similar window and then shave it down slightly so it'll fit. if you can find someone to do it right, then with the window sealant and moulding done, it should fit right without leakage. just a thought though...