<p>From what you described, you're not equipped (equipment, staff and experience) to make this worthwhile trying to print onsite. If you can't have photos viewable and printable shortly after shooting them (i.e. less than an hour), don't bother. My suggestion is instead of trying to print onsite, you get a SmugMug or other photo sales site. Print cards that direct people to the web gallery and give the cards to everyone you photograph. Say on the card that the photos will be viewable the day after the event. At the end of the event, go home, edit your photos and upload them. You can sleep the next day while people are looking and hopefully buying your shots. Also, some people may not have the time to spend or remember to seek you out at the end of the event to see their photos. Instead, they can see them at their leisure.</p>