I'm in the process of installing the doors in my coop and found the ultimate raccoon proof latch. It's located here and it's on sale!
http://www.hardwareandtools.com/Sta...ch-Combination-Locking-Hasp-033923011785.html
http://www.hardwareandtools.com/Sta...ch-Combination-Locking-Hasp-033923011785.html