Im really interested in doing something to reduce the amount of air getting trapped in the rear bumper to cut down on drag.
Not as a speed mod, to increase mpg (slightly).
NO, Im not cutting holes.....
So, who can make something like this?

Only...not so damn gargantuan
I have almost zero fabrication skills and wouldnt know where to get a sheet of aluminum anyway...what about expanding foam (if kept away from the muffler)?