Wants to do demanding work, preferably outdoors.
Gap year, knows what direction he does want to go when he does start school, and wants outdoor, demanding work…
You’re damn near 100% describing enlisting in the Army National Guard. He sounds smart so he would likely have a wide variety of job options in the Guard. You go to basic training (which everyone does) then your job training, which can be anywhere from 8 more weeks up to almost a year, depending on the job. So basic and job training would take up anywhere from 16 weeks to a year (his gap year). Then for the next 4-6 years (depending on his enlistment) he goes to his unit one weekend a month for training and a 2-week annual training period in the summer.
On top of all this, whatever his college degree was going to cost will dramatically decrease, if it’s not completely covered. Congress has thankfully (finally) increased some military benefits since the War on Terror period started, and there are some soldiers who actually make money by going to college, compared to kids coming out with tens or more thousands of dollars in debt.