As I begin to look at upgrading to a 370z, I've been looking for an alternative to drilling into the front bumper. Especially if you have the Nismo, you don't have that black piece of plastic to drill into. I know that Stillen makes one that screws into the tow hook, but the tow hook is off centered and having the plate to one side looks awkward to me.
After much digging around on the net I found this bracket. Looks like it doesn't drill into the front of the bumper but instead underneath the bumper. Also you can change the positioning to have positioned lower.
Skene Design License Plate Mount 
Thought I'd post it up for anyone else looking for an alternative.