I personally see mo problem with it, of course I am not the law though. As far as I know there is nothing in the constitutions broaching the subject. We all had letters on our cars. We never wore our lovelier or letters in the bar.
My only concern is this...if you are drinking and get in your car that is not good anyway you look at it. But if you are acting as DD then that show responsibility and SA should be proud to be represented by you.
just MHO