EdgarDonaldBalls asked me: "If you have the adapter, can you try and see if the face of the stereo fits through the gap?". The answer is no, not quite.
https://ibb.co/5j0GCjd
Is difficult to see well, but the unit does not quite pass through the gap...I'm guessing that will be a problem..? the adapter is also warped, though since I didn't put anything under the 'lifted' edge in this photo, it's not easy to guage the gap caused by the warping, but it's about a half inch or so.
https://ibb.co/6XwpkLG
Looks like I'll be sending it back for a refund, and the search goes on for one that will fit