@chakeubeam can print and sell you some.The only location for a third or middle mounted head would be under the license plate. Above it is a clear plastic shield on the grill which I believe is part of the adaptive cruise control.
I am quickly seeing the need for a 3D printer.
Yep the higher spots in green should do nicely, the ehads cover about a 24 inch radious around each of them so if you take a tape measure from the edge of each head to the outside corners make sure it's under 24 inches. Do you know what guns you face (or tell us where you drive)? The dual is generally good for everything less than DE though DE is spreading so at some point you should add a third head so you are covered against it in case it pops up near you... if DE is already in your area then go triple up front.