I would say that you first need to understand why he is having the problems at school. Is he capable of learning in a standard classroom environment? Is it his friends? Are you making him do his homework each day? Are you reviewing all his completed work and making him correct errors?
That being said, if the hunting is the premier father-son bonding time between you two, maybe instead of elminating that you should look for ways to get to know your son and understand what he is going through as you prepare and go on the hunt.