Personally, looking at that I'd have gone with a full upper block and maybe 1/6 to a quarter width each side on the bottom. IMO it's the upper grille blocks that are more aerodynamically effective.
I remember The RoadWarrior..To understand who he was, you have to go back to another time..the world was powered by the black fuel & the desert sprouted great cities..Gone now, swept away..two mighty warrior tribes went to war & touched off a blaze which engulfed them all. Without fuel, they were nothing..thundering machines sputtered & stopped..Only those mobile enough to scavenge, brutal enough to pillage would survive. The gangs took over the highways, ready to wage war for a tank of juice
its probably a little late for suggestions but I have seen where people have relocated their front plate lower (under the bumper) and used it as part of the grill block.
it gives the front of the car a cleaner look. may not be good for your application if you are already getting too warm for comfort.
You know, that's kinda funny you mentioned that. I bought the car from a state that doesn't have a front plate. so I had to buy the front plate mound from Honda. So when I first got it, the plate was down there, but on this car, it doesn't quite fit right. I thought about fiddling with my own custom mount, but I just wanted to have it look correct, and not attract any law enforcement...
I think most laws clearly state that the plate is to be mounted to the front bumper. Enforcement tends to be pretty lax, though; mainly people only get any enforcement activity if they completely lack the plate. Still I'd rather not attract attention by having it too far from where it's expected. I'm happy with my partial lower grille block license plate...