I had a Mk.3 mondeo and it was a bit tight to put a bike in as you describe. Boots are generally good at hiding wear and tear but roof linings are not and it doesn’t take much to make them tatty.
You also run into issues with the fork legs dragging back and forth over the lowered rear seats or slipping over the edge, having to drop the saddle, and bikes moving and the bars hitting the windows or just rattling against the glass.
A thick sheet and the bike laid in one above the other was easier and quicker.
Bikes in upright and sleeping space…you should get something like a Transit Connect!