for a belly pan, and even wheel covers, I would searusly think about something like polycarbinate because it's going to be less likely to shatter, it's what's used for safty glasses, or try air plane fabric and paint, you should be able to attach either one of these with metal edges that are pined on, or buttened on, or held on with small bolts and "T" nuts.
I consulted the provider who carries the polymer stuff. He told me that polycarb is durable when molded into "spheric" bodies; i.e. orb, elliptoid orb etc. or boxes. Otherwise he said it would be way too elastic and wobbly and when it wobbles it will tear from the pin-down areas.
As for aircraft material; I know of a carbon fiber provider but that stuff is astronomically expensive. I' d rather let it stay as is...
Thank you for the ideas though. I have rims which I am planning to equip with tiny splitters. (Please see attached pic of my car)