You don't need to do it all by yourself. Obviously it's not going to be easy since you apparently have multiple groups using the fields, but within the context of LL, it's possible to get the league to require coaches to assign parents to field work before and after games. And of course once they hit the big field, the players should take that duty over. Once you've got your workforce, the key is to train them to do it properly. That part is much easier with kids than parents.