I hunt with 3 fellas over the age of 65 the old man is 84 this year. From my observations the thing to do is go slow and easy. Find your water hole and just sit them out. If at all possible find a place the elk are moving through and be patient.
The weather advice is spot on. In one hour I was swatting at pecker gnats, wiping snow from my glasses and back to swatting the gnats. Find yourself good light warm clothes, water / wind proof layer, and put them in a good pack. I'm thinking down coat and pants, light / warm. Throw water, GPS, Compass, Knife, Saw or Hatchet, Game bags, Cordage,Whetstone, Lunch, Fire making supplies, First Aid supplies, and precious little else in that pack. If you find a good hide consider caching that stuff each evening. Too danged heavy to simply take it all for a walk each day. (you may need some of that stuff for the hike in each day but not all of it) Trust me every pound will add up and you will be tempted to leave your undershirt behind to avoid the weight.
As big and clumsy as they look, those Elk don't know they are not deer. They don't pussyfoot through the woods though, so be ready to shoot. I was used to flat land and could not believe how many Elk can hide in a small fold of hillside, to appear just 40 yards away silently.
Wear out some excersize equipment between now and Oct. you will not regret it. Let your Dr. know what you are up to especially the altitude part as some meds may need tweaking. I take some sort of pill for a few days to avoid altitude sickness, and quit one BP med. Dehydration is one of the bodies mechanisms to fight altitude, be aware and drink plenty, especially the first few days.
First and foremost remember this is all for fun.