Maybe do a diary project every evening for 5-10 min. or so where he writes down the most important bit of his day? Not a long project, but meaningful writing that connects to his experiences.
You'd have to structure it so that it feels rewarding and not burdensome or overwhelming, which may mean indicating a time limit, deciding carefully on how it will be produced (scribing, typing, handwriting), and deciding on a pleasant activity that always follows the writing session.
That camp sounds wonderful!
