Hey, don't worry about it, you'll just have to plan to ride slower than usual. Nothing will asplode, it will just be harder than if it was lower. Also, if you do go into the red zone, it will be noticeably harder to recover.

Independence Pass is beautiful and not that steep. You might not want to wait for October, though, too cold, possiblity of snow.

Also, I agree with Lanterne Rouge that is not a particularly safe route. If you must use that route, do not do it on a weekend. I just drove back and forth from the front range to Salida this weekend, and the traffic was bad. That section between km 40-60 on that linked route is particularly gnarly - twisty road, poor visibility, small/no shoulder, fast traffic. If you are trying to get 100 miles, I would start in Twin Lakes, ride over I.P. then do some more on the other side, there are great bike paths from Aspen to Carbondale and then you can go either north or south from carbondale and have nice roads.