Make sure he knows what to do if he gets 'lost'....stay put and use the whistle around his neck if needed....3 whistles = help.
Let him make mistakes....don't automatically jump in if he is doing something wrong. Let him figure it out on his own if possible. Also find a safe place to scramble up rocks....really fun.
Of course take clothes to keep warm and dry but let him (and you) get dirty and not have clean clothes every day. That may reduce your 60 lb pack quite a bit.
Before the trip have him draw a checkerboard on his sleeping pad. Out there have him look for dark and light small rocks to play checkers. If he has no idea of what that is....time to teach something that is not electronic.
This is the perfect time for him to start being comfortable with silence and peacefulness instead of constant craving to be busy or needing noise. Wilderness is a sacred place that deserves respect and attention.