I'd consider another cell, no use for a smartphone in the wilderness. I have an iPhone with a griffin survivor case, and a Nokia 5210. The people that need to, know both numbers. The iPhone gets turned off, and I can take spare battery's for the 5210 and insert them quickly, and unlike the iPhone I don't have to charge it every night if its getting used!
Now if wilderness was true wilderness, then you're looking at satellite phones etc, but my wilderness is normally just into the bush, less than an hour helicopter/less than 2 days hiking.
Potential of a big trip to the Yukon this summer, so I might be looking into this'd more seriously soon!