I had a gift certificate for american muscle and decided to give the magnetic blackout a shot. Mine fit perfectly around the gas cap, had to push it in a bit, it's a very snug fit. There are tiny gaps on the sides by the tailights, but both are even so I think it looks fine.
As far as it being rolled up. I laid it flat with some heavy books on top if for about 3 days. that helped but not enough. So I got out the iron,put a cloth on top of it and ironed it for about 20 minutes. Not only did it flatten out, but it really loosened it up and made it easier to get on around the gas cap.
I think it looks pretty good.