Thinking about it... if several thousand uninfected people converged on Banff AB, right in the Canadian Rockies, they might do pretty well. The town is behind the curve of a river, sits at the base of a truly impressive mountain, and has some pretty decent natural defenses. The bridges into town would be easily defended, there is a nearby airstrip large enough for small planes and helicopters, and there is running water. Since it's in the Rockies it would be a frozen town for a great part of the year, but the undead would freeze as well in most Deadworlds. I'd take a chance on that.