You might need to adjust your plans. If you have not conidtioned, have never been out west, and have never been to 10,000 feet, you WILL have issues. I live at 5000 feet, and did a hike to a little over 10,000 one day within about 3 hours (trail head was 8800). I was getting altitude sickness. Figure spending at least 2 days at 10,000 just to aclimate BEFORE hiking.
Also, I shot a cow elk last year by myself. I was less than 1/2 mile from my 4 wheeler. It took me 5 hours to skin, quarter, and pack the elk to my 4 wheeler by myself, in 5 trips. That was at 7000 and I am in decent shape. If you have never handled elk before, and have not put that much weight on your back (mine weighed about 60lbs per load), you will need to rethink your BIVY idea. I would guess for 2 people in GOOD shape to do 1 bull elk 4.5 miles would take an honest 2 full days sun up to sun down. It sucks, but thats the reality of it. It can turn a fun hunting trip into a night mare and wasted meat.
Thats my advice.
Marcial