As you can see from mine, I wanted the continuation of the black of the grill and onto the bonnet to be there, so i put a sticker numberplate underneath the nearside headlight.
I readily admit that it doesn't look ideal (although I have recently re-positioned it, and in real life it actually doesn't look that bad).
Yes, it is illegal...but I've been running it for a little short of a year now and have had no issues whatsoever!