I see them as a style element pulled from the 1970 Mustang front end mixed in with a Shelby style front end. ( I love that design )
I'm guessing that filling the pockets will do little to nothing for the aero. If anything, they might serve as an air curtain.
If you do fill the area, you could use a clear lexan material like that used to fill the light sockets on the Viper GTS.
You have a really nice looking car.
(Viper GTS - man what a fine looking machine !)