I don't think there is enough depth there. You should be able to easily remove the on board computer (above the DIN slot) and then remove the sunglass shelf.

I think there is either a bunch of climate control stuff back there or the transmission tunnel + carpet + sound deadening.

What's wrong with your normal DIN slot where the radio goes? In my 1995 M3 the RioCar fits perfectly, and looks very 'stock'.

Good luck!
Wes