Thanks a lot for all of your recommendations guys! This really helps. I'll try out a couple of different configs and see which works best.

Right now, I just hope mounting the radar head behind the plastic bumper cover isn't going to affect my range or off axis coverage too much. I don't really have any where else to mount it to. Currently, it is 3M double sided taped on top of the bumper pointing behind the plastic bumper cover.

If sitting on top of the metal bumper, would you recommend sticking the head (Curved portion) further forward past the metal bumper or can it be slightly recessed back sitting on the metal bumper? Just want to make sure I maximize as much as possible. I'll try to get a picture tonight.