The cuts you make to the single DIN console to get it to fit the double DIN cage aren't visible once everything is installed into it.
It never seems to be documented but the single din and double din ashtrays are also different.
Where single din has the cubby hole below the climate unit (the rubberised area behind the ashtray), OEM double din setup doesn't have this, and the console doesn't have the slots to accept this part. Instead the double din ashtray has a extra plastic section that covers the 8-10mm gap between the ashtray lid and the base of the climate control unit.
When cutting down a single din console you could also cut down the cubby hole 'floor'? 'base'? (I don't know what you'd want to call it), so that it meets the back of the single din ash tray and doesn't leave you with a hole that you're bound to lose your house keys in, or these days, even your whole phone could probably disappear down the gap. Or you could try and source a double din ashtray.
You also have to get hold off a double din climate unit, the single din ones don't fit unless you trim down the edges (scary job).