Ovis,
Have you ever shot sitka blacktails?
The reason I ask, is because most people, me included, always thought they were kind of small. They arent, they're actually pretty good sized...not real tall but stocky.
I dont know how you guys are intending to get your deer off the hill...but you wont fit a boned blacktail with head and cape in a day pack. Where we shot our deer, it would have been a real pain in the ass to drag them to the beach.
What we did was each of us took half a deer...front shoulder, hind quarter with the bone still in. One guy took the head and cape the other guy took the backstraps, loins, etc. That made a pretty balanced load for both of us and we could continue to hunt our way out.
I used my Mystery Ranch NICE frame with the 6500 CI bag as a daypack. Plenty of room for rain gear, spotting scope (a must in that country, saves a TON of walking), extra coat, etc. Plus plenty of room once you kill one for the meat, cape, etc.
I dont know, I'd shy away from a daypack...