There are 2 issues, the climbing and the altitude.

They are seperate issues.

Just speaking to the altitude issue. In my late teens /early 20s I did youth work with the YMCA. I prefered caravans where one did real camping and went different places, but I still did a lot of mountian camps. At just 6000-7000 feet altitude sickness could be significant. Go too hard the first day and you might end the day by puking your guts out for a few hours.

At that altitude just one day of not going crazy was almost always enough.

I always was able to keep my kids from over exerting enough that they never had this issue. Most of the time everyone did. When some other leader did not I knew I was in for an easy week, my kids learned I was worth listening to.

Still if yuo are fit yuo have a good chance of making the climbs yuo mention Ok. I've hiked Mt Baden-Powell (over 9400 feet) several times just leaving from Los Angeles the same day and zero problems.

BUT I hiked the trail, it could have been a very different story if I tried to run the trail or even tried to improve my time for hiking the trail.