Hatch latch problem... do I really have to cut a hole in my car?

[JDMeg]

The rivnut (also called nut-sert) would likely work for you. I work as an accessory installer and use these frequently for various mounts in thin metal. If you can't get the tool yourself, I'd wager some garages have one. If not, try somewhere that installs safety equipment on trucks (like rotating beacons, fire extinguishers, that sort of thing).