FWIW, here's a picture of the HPG Ute (plus compression panel, plus tripod scabbard from Sunrise Tactical Gear) that I run here in the Southern Appalachia's...
I've no first hand experience with your area of operation, but I'm thinking a day afield up there might mean layers and lots of 'em--not even counting a flyrod or two if dumb brook trout are (also) your thing.
Another option of course would be the Canadian Arc'Teryx--no doubt they're still living up to their bomb-proof-but-spendy reputation...I've always to shake out their Khard series, which seems tailor-made for photography...
Khard 45 Pack / Men's / Arc'teryx LEAF / Arc'teryx LEAF / Arc'teryx LEAF