Funny, but we did use an alternative site because the Army could not confirm the primary site was clear of just what you are talking about because there were cows where there should not have been cows.
Somewhat common occurrence to have unauthorized entry (and it could be rancher ranching wrong field at the wrong time, not necessarily illegals or intentional tresspassers) and the goal is to not kill anyone, just practice killing the right people, so . . . . .
Hmmmm..... Very interesting. God speed and good guidance systems. :>}