pillows or pillow cases, animal or nature shapes for the pillows
If they use the long tables for their dining area? You could layout one extra large light colored table covering, explain to the kids that either they can draw, color, paint graffiti all over it one day, or then the next day with a new tablecovering they can each pick a spot to eat at and they could paint or color in their place mats. Then their placemats can be cut out the last day of camp so that they could tie quilt it together or leave it as is to use at home.
scavenger hunts are always a hit at campgrounds...we have instigated them at family campgrounds too....asking other familes if they wanted to participate some do, some don't but both sides usually end up having fun with the hunt because some people are doers and others are watchers. Most families that don't initially join in, end up joining in by trying to give extra clues to the ones doing the searching.