I would go 58 with a shorter stem, as long as he can stand over it with one leg on a pedal at a stop. He'll appreciate not being hunched over on a four day trip.

Edit: I should say that all my personal bikes are setup this way due to how I'm built, so its my preference. I have extremely long legs and a very short torso for my height. I'm just over 6' and my mountain bike wound up being a 22"/XL Surly with a 90mm stem, and I still have the seatpost out most of the way.