That's the existing technique: If someone is behind cover, you must target a body part to hit them. Personally, I prefer to gauge "how much cover" with 10% increments, then roll a secondary d10. If I roll at or below the cover percentage, the bullet must defeat the BV of the cover before it hits the target. Mind you, this is really only good for clearly defined cover. Stuff like foliage and concealment should be compared to visibility charts (which are in the book already in reference to lighting conditions).

Clarity of purpose. Clarity of conscience.