A sufficient amount of volunteer support should be provided throughout the day to help unload the truck at the beginning of the day, hand out educational flyers throughout the day, and pack up the truck at the end of the day.  You can consider working with other campus departments, local non-profits, and other volunteer-based organizations to recruit volunteers. Recruiting about 25 volunteers is a good goal to aim for.
Recommended volunteer coverage:
10-12 volunteers for set up (typically about 7:30 - 9am)
5-8 for staffing the display throughout the day to engage passersby and hand out flyers
10-12 for take down (typically about 4 - 5:30pm)