Hats at a wedding!?!?!?!?

Okay so my dad has always worn a baseball hat everywhere we go whatever we do (I mean except pictures) so I wouldnt think of asking him not to wear a hat at the wedding (he doesnt look like my dad with out one) So I was thinking of having him wear a Fedora or something of that nature to walk me down the aisle in. Its more of a casual ceremony and no one will be wearing tux's. My dad would like to wear a jacket or a nice suit. Is this wrong??? Or do you think it will look fine?