I think it would be easy enough to hook up. Nick from tankhobby dot com makes targets that light up with IR hits and he sells them for about $20 us. On request, he'd probably hook a small relay into the board for you to use as a switching device, and then you could wire up your gate raising/lowering electrics. I'd suggest using a spring loaded barrier triggered by a solenoid, or in the alternative, a servo. Its a good idea, let us know what you build as it's quite interesting.