Pads definitely do help with warmth, which is especially a concern in AK. I've tried a few inflateable thermarests, the old ridge rest, and the slightly newer z-rest. Inflateable pads take longer to set up; you have to wait for them to fill with air, or else blow them up by mouth. I've heard doing the latter can make them mildewy on the inside. No biggie, but it sounds gross.

Inflateables get the nod for comfort, but I can't tell any difference between them and closed cell pads for warmth, at least not at first. Closed cell pads will compress after a few months or years of use depending on how much you use them, but they're cheap to replace.

Durability is a concern for me. Closed cell pads have nothing to hurt, so they can get chewed up by brush and still work fine. You can also trim them to any size you want. I even use my pad in lieu of a tent footprint when I use a bivy. Inflateables can puncture, so it's a good idea to keep a patch kit with you.

Finding a place to stash a pad can be a bit of an issue. If your pack's large enough or you're using a short pad, you can either fold up the pad and use it as back padding inside the pack, or you can let it unroll in there so it stiffens the sides, then put your gear in the middle. I used to lash my pads horizontally on the outside of my pack, but it would always get hung up on brush that way.

I think Gossamer Gear makes thin pads for the purpose of warmth rather than comfort. Might be worth googling.