I too have thought of this numerous times, but discarded it for two reasons:
Firstly, if you attach it to the holes in the lower front grille, then the shape of the body angles the plate, and it looks a bit weird. Where would you be looking to attach it to Coco?
Secondly, when looking at it, I cant help but picturing a rabbit with its front teeth out!!
ETTO though

A guy at a local meet I go to has put a 3/4 plate right in the centre of that lower front grille - as well as blocking air to the radiator, it looks fecking bad!
I just dont know of a decent front numberplate solution really, apart from JoesGTI but that is kinda illegal :S
Although give me time, I may post up tomorrow something that might be worth considering...........