april, I was thinking the same thing! I was going to get some thick plastic and put it between the case and the keypad (with the keypad mounting inbehind). I also like markB's idea of mounting the display behind lexan - this will waterproof it and i can just glue it. Awesome!
Also, about the name, it was originally intended to be an alarm but repurposed midway through. I think a "Keyless Entry" system would be a better name.
As for tamper-proof keypads, I dont need to go to that much trouble. To make a long story short, pesticide regulations now require that all doors to pesticide rooms (agricultural, anyway) be locked at all times. This can be somewhat of an inconvenience, needing to go in and out several times a day.
With a Keyless Entry system, the room is still 'secure' but you need only enter a passcode, rather than have a physical key. This way, anyone who knows the passcode can get in, without having to borrow/duplicate the key.
Thanks for all the warm comments!