I can't think of anything better than the tool man thing that @Eagledad suggested.
Other than that, hype the fun things. Talk about the campfire. Roasting sugar, skits, the whole thing. While they won't cook their meals they can help decide what they want to eat. Give them 3 options and have them vote. If you're experienced with dutch ovens and are willing to make a cake or brownies, tell them you're going to bring an oven - and the whole cake thing, of course.
If they feel good about sleeping and food, that should cover most of their fears.