Assuming the snow and frozen earth in Alaska is roughly similar to that experienced in Minnesota, 38s will be fine; I use 32mm cyclocross tires, and really never have trouble with them.

I had a choice to make with the FrankenHybrid; I put a Karate Monkey fork on it to get rid of the stupid heavy stupid useless stupid crappy stupid suspension fork. The KM fork comes with disc tabs already mounted. So, obviously, running with a disc up front would make total sense. But-and-however, I decided to go with V brakes; it's by far the cheaper alternative, and the icing problem isn't insurmountable. I do make a point of tapping the brakes every quarter mile or so, just to keep the brake track cleaned off. It works pretty well, though the very first stop of the commute in the morning tends to run a little long.