Well, the 50-miler is a week long hike. Last time (a few years ago), they only had one really long day, and that wasn't intended, but just worked out that way. It was trickier then than it would be now, too -- they recommend the backpacks not be more than 30% of their body weight, and at the time, he was a 94 (iirc) pound puny guy. Now he's put on height and a bunch more weight (last I knew, he was in the 140's), so 30% is much easier. Some of the equipment is the same weight, whether the guy carrying it is 90 lbs or 200lbs. BTW, I'm not sure if the 50 miler is open to below 1st class. They have an alternate campout for the rest, at a regular scout camp, rather than in the wilderness.