just a thought.
In the 90s when i was reading all the audio mags i saw a US one where the guy had a Vette which has a stereo kind of like in a VT-VZ where it blends into the dash in a double din config

what he did was glued the whole face together and cuteverything off behind it then glued a flat panel on the back.

From the front it just looked like a stock head unit and it even had leds that lit up when ignition was on
when he wanted to listen to something the panel could flip around (hinged at the top and bottom - middle) and there was a facia mounted on the flat panel at the back

For those of you who remember, the old FM modulators for fitting stackers to standard head units? it was like that but a stand alone job

the complete panel where the stock stereo is could become a hinge with a new head unit behind that, along with extra switches if wanted

mind you you can just have one of those things that plug into the cigarette lighter and tune throug the FM radio f your stock unit played ok