As quick as a jump height is done running you should post the results. Award rosettes at a time where you'll get a crowd of appreciative exhibitors, but not slow down the show. Put a barrier around the scorekeeping table to keep the exhibitors from pestering you. These people might receive a certificate for a free class. For gate stewards and ring stewards, recruit people from your beginning agility classes and obedience classes.
Kids can help out as runners and leash stewards.
For building courses, assign one person as chief course builder for each ring for the entire weekend. Club members, whether running a dog or not, pitch in to actually build the courses. Write up job descriptions and hand these out at the mock trial. Second, have a meeting on Friday evening with the judges so that they have a chance to explain things to the workers. Also, most judges are very willing to assist the green workers - answering questions, directing them when necessary, etc.