I've not weighed one but I would say you can pack 1 bone-in hind quarter, but not 2 (and do it safely). IIRC, the last one I packed out, I took the hind quarters out separately, then put both fronts, backstraps, tenderloins, and neck meat all in one bag, which was heavier than the individual...
This is purely anecdotal, but I have found that Tylenol Sinus helps me if I get an altitude headache (in addition to the hydrate/hydrate/hydrate already mentioned). I live here, but if I'm going to altitude I always have some with me.
I'm originally from SW PA myself, down in the Mon Valley area (south of Pittsburgh); got tired of driving into Oakland every day working at UPMC Presby and escaped to CO in '94.
I got caught above timberline once when scouting for sheep when a fast moving electrical storm blew over a ridge and it is the only time I have ever been truly scared in the mountains.
Just got on here; I've lived in Grand Junction CO for the past 24 years, moved here from western PA ( I consider it an escape). I've been fortunate to have been able to hunt sheep & goats here in CO and chase muleys/elk somewhere/somehow every year. I really like the high country/backcountry...