protect my dogs

if someone climbs my 5-6 ft fence with signs beware of dog, no trespass, etc. heavy locked gates are my dogs safe? am i liable? if they stick hands, or face into fence and antagonize dogs and get bit are my dogs safe? am i liable? if i walk dogs on 4ft leash and other person defies my direct order keep back and lets their dog approach and their dog is bit are my dogs safe? am i liable? what other actions should i take beside fence and signs to ensure i am being overly responsible and any and all injuries are the sole responsibility of the bitten party who went over and above to be bitten and be in that position? i currently live in a non animal state where they order murder of animals by the hour regardless of their innocence so these answers are to save their lives in the event of the worst nightmare scenario.