Kevin,
I live in the Denver area. I'll be out there for archery either first or second week of September. I've back packed a couple times up there, not to worried about getting in or out. More worried about how skinny almost every basin is and if I'll be able to get to a glassing spot in the morning without kicking everything up.
Depending on where your hunting in CO, glassing can be pretty difficult due to the thickness of the woods , even once you get up top often you're going to have your views completely blocked right in front of you by the trees and then looking down your going to see a lot of trees. That said, i hunt the deep timber so this could mostly be a "me" problem, haha.
To your concern, certainly possible to bump elk in the dark, it happens, not much to do about it. If you know where your expecting to find elk you can plan around that and dont forget to plan for the thermals in the morning. You will not want to be hunting down on elk until around 11-am, depending on the area, when the thermals have made the switch fully to the uphill direction.
Personally, and this is how i spend my mornings hunting the deep timber, i get up long before dawn, hike halfway up to where i think elk are gonna be, and then sit down and shiver in the cold listening for bugles in the dark. Once i hear some i make a move towards them or, if, as it happens, they are right above me, i will wait for hunting hours and then start hunting my way up hill. This way im taking advantage of the thermals in the morning coming downhill and once they start swirling and switching ill just take a break, probably do some calling, and then start hunting across the slope or downhill. Your not gonna win the game with the wind at your back, ever.
Maybe more advice then you cared for, no idea how much hunting experience you have here in the mountains of CO