If you are a member of Workcamper.com, they have a section where you can post looking for what you are wanting. You make the post, and potential "employers" can see it and contact you. Also there are private campgrounds that want volunteers for work campers. We worked at one last summer in the Wisconsin Dells, we worked (not hard), in exchange for our campsite. Also on volunteer.gov you can look for what state you want to work in, and it will give you federal, state & some county campgrounds looking for volunteers.