I will agree that there ARE those (whom are elderly), CAN hike incredible distances over a long period of time - without "crashing" due to the environment/weather.
With some sort of comparison - I'm 55, been hiking for years - so you could say I'm more than just a daily hiker. What many here might not know about me - is that I am a smoker (yeah, I know, shame on me). Been one for 35 years and I STILL can go out, hike for 10 to 12 hours - covering miles of wilderness all with just 2.5 liters of electrolyte water all while carrying 50lbs of gear and get back to my vehicle before dark. I'll struggle, but will complete the route. My point is, I can see the RIGHT type of elderly man (who isn't a smoker) hiking into a tough area and make it back - but to say an 80 year old packed with gear (water, suitcase etc.) - make their way through some of the toughest terrain known to anyone, proceed to, mine out some Ore, is really hard to swallow. I have to say - though there are tough ones out there - common sense overrules the exceptional though. From what I know about those who lived back then in the 1800's - were a rare breed of tough-ones that don't really exist these days, but hearing a lot of these stories of men in the late 70's - reaching sites (Mines, caves, etc.) without having issues is just so hard to believe, I have to fall back on common sense. Again, as Geoff states - there are those who are exceptionally fit in regards to endurance - allowing them to cover great distances, but that certainly isn't the average man. Of course - were those back then, average people? I have to say no. Those back then struggled just for the basics and would do ANYTHING to survive and complete their task. I think we can all agree on that.
So - as we could go back and forth (as I did above with myself), I think we can all agree, that those back then were just survivors of anything that came their way in Life. Al Senner did some incredible distances as well - though he was known to ride most of the time - there were times he had to climb up that North Western side, just to reach his camp, not to mention he did that during snow storms as well - providing you believe the story by Helen Corbin.
What I will say about all of this - is that in the end, I have to go with Joe on his assessment. He walked the path that supposedly Wagoner did take, as well as the Dutchman who did similar hikes down similar paths - as everywhere in those Supes is tough to get to. He got to see first hand the difficulties that can arise if one isn't prepared. Not to mention that Joe was on an actual trail. I don't believe those back then had the same trails as we have today. I would think, many times - those back then would have to walk "off trail" and into the thick of things - just to reach a desired location that's supposedly hidden from everyone else.
All this said - a thought comes to mind, based on all of this discussion. If most of us think these men DIDN'T walk/hike those distances like the stories would have you believe- then that leaves me to believe the Wagoner's location AND the Dutchman's location are not that far into the Wilderness. In this thinking - things would make more sense in how these men conducted their business, being able to get in there within a day - and then get out before dark. Something just isn't right about those kind of details. Once one (like Joe), gets out there - it just gets harder and harder to believe what we've all been told about these old timers.