Aren't the side impact bags in the doors on the Crossfire? I know in many cars they're in the side bolsters of the seats so covers would indeed be an issue, but in the Crossfire??

As for the sheepskin seat covers in general, it's an old school fix for hot leather in a convertible. They used to be incredibly common and considered a very classy fix for this issue on older Mercedes SL cars. Long wearing, cooler in summer and warmer in winter. Get a good set and I don't see a problem with them in these cars at all.