We actually have discussed spending two nights at the bottom, and already have things set to stop at the halfway point on the way up. Far as the heat goes, I'm hoping that with a 4a start time we can make it down fairly early. I once ran a marathon with about three 3 mile runs under my belt 6 months prior... Yulp. I was sore. We're headed out tomorrow to do some hiking around mid day here in Phoenix to see how we are doing with the heat, mostly as a practice run for an "uh oh" moment. We shall see.