[Sunwapta]

Yes - "flap in the breeze" and then tear or wear rapidly. Glueing, riveting laminating on nylon strapping might do the trick.

There's kevlar, nomex and probably lots of others - at a price.

Back to my list - I'd think the underbelly spoilers would be the easiest modification. You could probably pull those old aluminum rear spoilers off wrecked suburbans, etc. and retrofit them underneath at a mild downward angle. Or just stretch across some tin flashing and bend it down where needed to smooth the airflow.

hey - maybe retrofit a couple of those black plastic hood protectors/ bug deflectors (go underneath and bolt a couple on upside down).