Instead of laser why not go with a simple IR beam like they use in stores to indicate foot traffic? Cheaper and simpler by far.
I would also suggest contacting the Arizona Department of Fish and Game at http://www.gf.state.az.us .
They have been using remotely triggered cameras to track the movements of Jaguars in SE Arizona. Yes, we have Jaguars here. They used to roam as far north as the Grand Canyon. While thought extinct in the state, in the late 90s a rancher cornered one while hunting and wisely decided to shoot film instead of lead. The state then decided to look for Jaguars. They have found several using remotely triggered cameras.
From what I understand they have dozens of cameras out at one time, so whatever system they use is most likely pretty cheap. It is also durable. Contacting them could be valuable.