Look up “honda civic interior bike attachment”
There are various official and unofficial options for bike mounts in the rear using the fork axle.
Some use the spare wheel space for the mount so you can’t have a spare wheel or junk in that space, though since I was looking some years back it seems there are other options now.
Looks like Tourer gets multiple bike version.
I just lay mine on the side. Can stack a few bikes with some protection in between. Would be interested in getting a nice interior mount though.
p.s. I wouldn’t put bikes in upside down if it’s a long trip, especially if it’s been muddy, hose bikes and then shove in the car. As I found, seized headset as water must have collected in the headset instead of drained out. 😉