Downhill is the hard part... The last three miles down Mount Manitou are the worst. Add in the increasing heat the lower you get and it's really challenging.
Agree with prior post - talk to the Incline Club people.
One huge thing to think about - most of the people in the race are fast hiking, not really running, for most of the race. I volunteered at the Cirque aid station for about 5 years and the top 15 men and maybe 5 women were actually running that high. So train on trails and train the fast hiking technique. Also, the oddest things sound appealing at 13000' (that's where my aid station was) - Sugar wafer cookies were always a big hit. It's a long way between aid stations, so find some kind of hydration pack or belt that you KNOW will be comfortable. And please - PICK UP ALL YOUR TRASH!!! Nothing is more fun the tracking down every cup, gel wrapper and shred of garbage before hiking back up the mountain with all of it on our backs. At most of the aid stations, the volunteers have hiked in for the Ascent, carrying it all down or up and the Marathon shift has to pack it all out. All of it, garbage cans and everything. Carrying a full garbage can 1.5 miles up to the summit with lightening all around and still needing to pick up trash isn't fun. (rant over)
Pace yourself - don't waste energy on Mount Manitou passing people - otherwise it will be a death march after A-frame.
Between A-frame and the summit both coming up and going down gets crazy. I did the marathon back in 1997 and the lead men were coming down just after I passed A-Frame and they actually have the right of way. So be prepared to step out of the way - and it will get busy the closer you get to the summit.
Altitude is a different matter - if you don't know how your body will respond, the current school of thought is to show up as close to the race as you can. Getting here a week before is actually the worst because your body has just started to aclimatate - or so that's what people say. I'm of no help with that, being a native and all that.
Good luck, have fun!
Vale!
Tracy T
http://www.thelencoaching.com Some light reading:::
http://www.tracythelen.blogspot.com