I don't know how
@JimN does it, but he puts his bike in his Fit standing up and it's awesome.
When I'm willing to put pants on, I'll go take a pic. I basically have a 2x6 or a 2x8 that I cut to fit the floor of the cargo area right by the hatch, and I screwed a fork mount into that. I take off the front wheel of the bike, and it fits in with the rear wheel between the front seats, and the fork screws into the mount. This has worked with a medium and large 29er, although they both had dropper posts. I would put the post down, put the bike in, and hit the lever to put the seat up. It would go most of the way up and hit the ceiling, helping hold the bike in place.
The fatty barely fits, because the tires just barely wedge into the space between the seats. It doesn't have a dropper post, but it's a medium frame and the post apparently isn't too tall. My downhill bike doesn't fit, because it's way to tall in the front. I am a huge fan of this setup though. I like to have my bike with me all the time so I can squeeze in a ride whenever, and I just feel safer with it locked in the car.