Hello gburks83.
A motion sensor fitted with a shield (such as a toilet paper core) could be aimed across the driveway at a target board. The target board (or maybe a large enough plant) keeps the motion sensor from picking up any infrared from behind the board. A plastic rain protector cut from a bottle could be placed over the motion sensor and its shield.
Check out this link:
Motion Sensor Shield
In your case, the paper core would need to be 4" long or more?
Victor Maletic.