im a northern hunter, ive hunted most the places you listed and to be honest the idea of a extreme conditions rifle is somewhat laughable now that i i think of it. ive used hunted with remington 700's, rem 7's, winchester 70's and 94's, savege 110's and 99's, ruger m77's and no.1's, and weatherby vangaurds and mk.5's. ive never had a jam or freeze up that was at fault of the rifle while hunting. infact any problems ive had with a majority of my gear could probably be drawn to user error. the only thing that i might want on a rifle is a weather proof stock of some sort but all other so called "extreme condition" rifles are only named that to sell you more features which will probably wont be needed. my biggest advice is to learn how to deal with the extreme conditions (winterizing a rifle, optics and so on) rather then trying to buy preparedness.