I have been thinking that if you are going to all this effort to seal the bottom of the car why not continue the same piece out into the front fenders only except for where the tires and suspension pieces are.
Yesterday I stopped and talked to this guy with a 76' 280 at an eckerds pharmacy and he had the little splash guard but it was pretty rusty. In fact his whole car was rusty and beat up but he had some nice pieces.