I know it's not exactly the same, but I needed to put a PMR in my 2011, so I got one where the facia is able to be placed remotely.
I mounted the main unit in the rear, behind the trim, in the same side as the fuel filler. There is a nice bit of room there, and in my case, it put it nice and close to the antenna.
I then made a pair of stainless steel brackets up, that fit onto a pair of screw that hold the radio in, and run round the gap between the central facia, and the dash., where the front of the radio then mounts.
Sorry, for some reason, this one has been on the Christmas Spirit, and won't stand up.
It might give you some ideas.