The guy with the mustang built his roof from carbon fiber and honeycomb sandwich so it DID have structural integrity. Of course he also had a full cage. He is building every panel on the car out of carbon fiber.

Carbon fiber isn't any harder to work with than fiberglass if you are just doing it for appearance (dash pads, gauge holders, etc). The trick honeycomb vaccuum formed structural panels are obviously more work. The big deal with carbon fiber is that if you are leaving it clear, you have to make sure the weave looks good, otherwise, its just like fiberglass.