Some people take to backpacking like a duck to water. Others just can't adjust to it. The chances are good your partner will be able to enjoy a long backpack with you, but the advice to take him on a couple of short overnights, maybe under less than perfect weather conditions, is good advice. Once you are on a long trail you could easily confront rain, cold, dirt, bugs, hunger, thirst, minor injuries, the whole list of things that must be contended with when you hike for more than a few days.

Long canoe trips are similar, but not the same. Go out together a couple of times before you drag him off for a 180km adventure. You won't regret it.