I’m voting for the Appalachians. Supposedly other than the dead girl friend, he didn’t have many friends. He is also familiar with the area having previously disappeared for 3 months in the range. Go with what you know...
If he is an outdoorsman he could stay on the trail for years with little contact with the outside world. If he did a Yo-Yo staying in the south during winter and up north in summer one could live in the trail for years. Trail types are a close knit group and would shun LEO especially the ones who are 420 friendly. Barter is big on the trail trading hunted meat and fish for supplies is common. Personally I’d be on a beach in the Gulf States or in Moscow at a night club getting pissed far out of reach of uncle suggar.