You did great Dad!!!!
Some thoughts ...
-Hopefully he has rain gear
-Hopefully he has a warm jacket (fleece?)
-I might have added some 4" & 3" gauze pads to his FAK - mostly to handle big knee scrapes; he's already got the duct tape. I find a small pack of baby wipes useful for cleaning wounds when soap isn't available.
-Hat, Sunscreen, & Lip balm
-Insect Repellant