Just eyeballing it, it's about 600-700 ft from the center of the pad to the tree line, so perfectly doable -- would cameras have been watching the tree line? If someone had shot from the top of a roof or something, I'd think cameras would have caught him leaving/hiding. It would be very, very obvious they shouldn't be there.
Leaving before anyone could notice you would be a bit more of a problem.
Leaving before anyone could notice you would be a bit more of a problem.