Should the salaries of high school coaches be supplemented by parent booster organizations?

My sons play High School soccer, and some of our fundraising money goes to supplementing the coach's salary. He runs 2 training sessions per week through the entire summer before the fall playing season begins, and coaches indoor tournaments and teaches the players weight training following the Fall playing season in the winter and spring. Should this extra effort be funded by the parents of the players? Should the coach do it without additional pay? Should we lobby the school board to pay coaches more than the standard weekly coaches salary payed only during the playing season?