License plate size for the current S60

Hello guys, I need your help. In one month I have to register my new S60 and I wonder if it would be chic to have the plates made slightly smaller than the standard parts. However, the dealer didn’t think that would go ahead, since a holder in standard size is already mounted from the factory side. What does that look like in the back, someone knows that? Can you make it smaller there, or does it look weird / or doesn’t go like that?