I don't feel unarmed when I'm packing a .30/06, and while a .30/06 has a distinct edge over the .308, (and yes I have both) the difference in performance doesn't justify swapping out the .308, provided its suitable for use as a hunting rifle in the first place. A rifle you are thoroughly familiar with trumps a more powerful one you have to learn. Getting ammo and handloading supplies into remote communities can be a frustrating, time consuming, and expensive proposition. so take in as much as you can when you go. Barnes TSXs in 165 or a 180 gr are excellent deep penetrating bullets, that will stand up to high velocity, close range impacts on heavy game when fired from a .308, .30/06 or a .300 magnum. If you handload you should have at least a few for special occasions. Most of the time 165 gr Interlocks work fine, caribou aren't difficult to kill, Interlocks provide sufficient accuracy to enable you to make 200 yard head shots on seals, and they'll reach way out there if you have the opportunity on a wolf.
If a new rifle is on the agenda, stay clear of actions that use plunger ejectors, these are particularly prone to failure if exposed to the elements for an extended period of time without constant vigilance, particularly around salt water. A good quality fiberglass stock, a CRF action, a stainless barrel, iron sights, quality QD rings and a pair of scopes is where I'd start. If you want more power than you can manage with your .308, don't stray too far above your known recoil tolerance. A 9.3X62 or a .35 Whelen represent a significant step up from your .308, without being terribly intimidating, but don't expect to find ammo at the local Co-op or Northern Store; a 12 ga and a .22 rimfire that you can get ammo for, trumps the big centerfire rifle that can't be replenished. Having said that, I don't share the northern native's enthusiasm for .22 centerfires, and I wouldn't choose a .223 or a .22-250 as my primary hunting rifle simply because that's what everyone else uses.
For use in the cold, no lube is better than lube that will gum at low temperatures. Recently I discovered that Fluid Film seems to work pretty well in the cold. After being left outdoors for an hour at -35, with the bolt soaked down in this stuff, my AR-15 never missed a beat. On a previous outing with mil-spec "Arctic Oil for Weapons" it was a clumsy single shot. During the summer, beware of rust. As I stated earlier, the plunger ejector in a push feed rifle will seize, if your shotgun has a steel magazine follower, it will rust to the magazine tube, and without regular attention, your expensive QD rings will become permanent. The barrel might no longer remove easily from your pump shotgun, and the magazine cap might require vice grips to loosen. A little grease is beneficial where there is steel to steel contact on parts that don't normally move. Another problem encountered with some firearms is that the finish will not stand up to bug dope. If you can afford it, an application of CeraKote or KG GunKote would be a benefit.