well...
I would claim ignorance and that you bought the car this way, and step around and say, "hmmm where would the plate go? I do not see indentations etc.. for a plate to mount to."
If he says it should be a spot there and it was modified, just say ahhh, I did not see any spot so I thought it was just like this on an old car, and thank the officer for the heads up.
