Re: Whichever way you slice it
When I can get reliable, free GPS and comms in the middle of the Sahara, I will be only too happy to do exactly that - until then, however, I'll have to do it differently.*
GPS is freely available all over the Sahara, as well as the Gobi and Atacama deserts, Greenland, Namibia, and whatever inaccessible location you feel you have to hike into and out of.
Comms may be unavailable, but that's neither the smartphone's fault nor will it be solved by taking a Pi. And lack of comms won't stop a smartphone from working as a camera and an ad-hoc file server.