I have been driving with no front plates in Illinois, which requires them, for the past twenty years. I was only pulled over once, when the NSX was new - and I think the cop just wanted to check the car out, because he had never seen one up close before.
I do keep the extra plate inside the car, in case I am pulled over. (It's possible the cops might be worried that you're using the two plates on two different cars, and that would alleviate that concern.)
If I were pulled over, I think I would probably be honest and politely say that it spoils the looks and many other states don't require them. And even if I got a ticket, it wouldn't be a moving violation anyway.
I would not want to place my plate where it blocks the radiator flow, though - so if I were forced to use it, I would do so with the stock bracket.