I have seen the face plate mounted as part of the overhead console, wires run down inside the passenger A pillar trim and the radio mounted in the dash next to the glove box. There is actually a pretty good amount of room back there.
Also seen it mounted where you initially held it with the radio mounted under the rear cup holder in the center console. A pretty good sized hole under those cup holders.
Important thing to me is subtlety. The more factory appearing the less chance of it inviting thieves. I used to always pull the mic out and toss it in the glove box or center console.
N1RIC since 1995.
Maybe just mount it in the driver door pocket then?? Its pretty huge