Thinking of actions:
1. The van is 125 yards from NE building so maybe under 200 yards from Sean?
2. How "windowless" it is? Windshield (tinted)? Driver's door window (tinted)? The most interesting thing is whether Sean can see the driver.
3. Now, if Sean can see the driver, the question is about penalties... Say, the heart/torso have sitting (-2) and some cover (-2) and maybe some darkness (-X) if behind tinted glass? And for the thead it's just darkness? I am not sure if Sean can ignore point darkness while otherwise in daylight.