In Qld it is Illegal to have bent plates, they call it defacing government issue items, or some shit like that........However i have only ever heard of ONE person being booked for it.
It may depend how nice you are to the officer that pulls you over.
I tend to use small brackets that screw into the underside of the top section of the bar and then are bent upwards, keeps the plate away from the bar. Works a treat. About 45cents each from bunnings