I dunno, my first (and hopefully not last) elk hunting trip wasn't with an outfitter, but rather with my buddy's dad (who used to guide and grew up in the area), but we hiked 6 miles (and 2500 feet elevation) leading pack horses to sleep in a homemade (on the spot, out of a lot of tarps and a lot of rope) tent in the last rifle season. Morning temps in the tent were between 0 and 5 F, I didn't sleep a bit the first 2 nights (the 50+ mph wind and snow blowing in through the tarps didn't help), we ate mountain house meals all week, had to carry our water from a spring up the hill a ways, and I only saw the hind end of one elk for a split second, and then had a good look at a spike that I couldn't shoot.
And I can't wait to go back.
Even if I didn't really get acclimated to the altitude til the last day of our hunt

You can get in shape (which I did fairly well), but it's still hard to prepare for 10,000 feet when the highest point around where you live is 3000 feet.
My point is (if I have one) is that you don't go Elk hunting expecting a walk in the park. I don't think I would head into the Rockies in the middle of summer without a cold weather sleeping bag, just in case. Even if the tent had been heated, heaters can break down, right?