First off, if there are any wilderness rehab programs, they are gonna be very expensive. Second, your son would have to agree to go and agree to stay. He is an adult and has the right to live his life well or screw it up. There are all sorts of treatment programs/rehab options out there.
Those wilderness/bootcamp programs can indeed be very effective. We sent one of our sons to one when he was 14 for a year and it made a world of difference. He is now a healthy, productive college student of 18. But that program cost over $50,000 and insurance did not pay a penny of it. Most of those programs can't keep the kids beyond 18 unless it is court ordered.