Most guys make the wheel skirts with Coroplast--my current version is of that stuff. If you don't want to drill the body for mounts you can make clips. You can see what I did, using MetroMPG's design as a model, on
my build thread. You can also make the skirts with aluminum sheet, which I have been planning to use. But I might experiment with a plasti-dip coating on the coroplast (to hide corrugated appearance) and then the OEM paint color I bought online.
Grill blocks can be painted too, of course.
You could also attempt a more radical project, such as a kamm back or especially a boat tail. SInce you're getting in painted... how good are your fabrication skills? Mine are so-so, but if you are really skilled... well boat tail that thing and get some OEM paint on it!
jAMES