D.I.Y. Mod - one piece of 1"x2"x10" PVC trim board and two machine screws w/ nuts and washers AND the factory license plate frame (I am in USA, other countries may have a different frame... I dunno!) Here's my story...
I recently bought a NEW 2018 (yeah, I know the 2019's are out, but I wanted a manual SEDAN, and I found one in California, so I bought it!) Anyway, as anyone living in a "front-plate-state" knows, the factory mount for the gen 3 front plate is, shall we say, UG-LY! I looked for an aftermarket mount, and the only one I found was one which mounted off-center and that looked almost as bad as the factory mount in the middle of the grill.
So, I looked at it and said, "I can do better!" And I think I did! At first I thought I would build a new frame holder out of PVC, but after working on that for an hour and a half and trying to fit it to the car, I realized the fix is MUCH easier than that.
I already had removed the factory plate holder from the center of the grill. I took that piece and noted three rectangular protrusions on the bottom back of the holder that prevented it from simply being mounted to the lower lip of the fascia. I cut those off, along with the two smaller clip-like protrusions an inch or so above them (toward the center-back of the plate holder). I then took a 1" x 2" x 10" piece of PVC and drilled two holes one inch in from each end. These will line up with the mounting holes in the factory plate holder.
You then take 2 - 1/4" x 3" stainless-steel hex-head screws and insert into the drilled holes and "whack" them into the PVC so the heads are "captured" and won't turn when you thread on the washers and nuts. Insert this assembly through the lower opening in the grill (below the main grill). You can now center it on the grill with the screws facing out, take the altered factory plate holder and assemble it over the screws sticking out from the lower grill and tighten it down. I used washers (to keep the nut from going through the plate holder holes and lock washers, but IF this loosens over time I will use a second nut on the screw end as a "jamb" nut instead. I also glued some weather stripping to the back of the factory plate holder where the protrusions where sawed off, just so it doesn't scrape the lower fascia where it makes contact (even though that's behind the plate.)
Total time to do the disassembly, mods and reassembly, about 1 hour... it was EASY. I hope this is fairly clear, I think you'll understand better after you take the plate mount off from that RIDICULOUS location in the middle of the grill... whoever thought that was a good design?!?
I am attaching an image of the finished product. Sorry, I didn't take pictures of the mods and the assembly during the re-installation. If someone wants step-by-step directions WITH pictures I will take mine apart again and document it, but I think you can figure it out from this description... I hope!