Put a pole up at the gate that was hit the most. 8'-10' up place large wooden box (painted Black) drill one hole 1.5" on bottom and one hole on each side that run along fence line. Attach "Video Camera" sign to pole. (Like this one)
Monitored By Video Camera Sign, Security CCTV Sign, SKU: S-4212 That might scare any kids who are screwing with your gates.