Glowsticks are much better, particularly multi-colored necklaces and bracelets. The necklaces can be a lot of fun for playing night games, and are great on bikes and wagons to help keep other people from running into you. The playa can get very hot during the day, and quite chilly at night. Loose, breathable clothes provide comfort and protection from the sun, and can be layered with warmer things as the sun goes down. Some kids are comfortable with going naked, but need to be protected from sunburn.
Hats are a good idea, as are sunglasses.
The dry, alkaline playa dust can be hard on tender feet, so socks are a good idea, even with sandals. Watch for blisters, and always carry some moleskin to keep blisters from getting out of control. This is one of the main points. Be sure you've got some things that are fun for the kids to do while you're hanging out at camp. Bring art projects, body paints, costumes, water guns, and anything that contributes to the function of the camp.