Just returned from my trip, verdict.....iphone GPS not so hot without cell assistance!
It did work without any cell reception, and was accurate for the first leg of my trip, but about an hour after I lost cell reception in the foothills around Iowa hill in the Tahoe National Forest, the GPS threw me about an eighth of a mile off of where I actually was.
I checked the GPS every 10 minutes or so over the day all over the TNF and down to Hell Hole Reservoir and it was consistently off by quite a bit (sometimes over a mile). The compass also reoriented itself at random which proved to be the most frustrating.
I'm now in the market for a good GPS, any suggestions?
2009 Tacoma TRD 4x4 Access cab, Toytec 3.5" coilovers, rear add a leafs, Bilsteins and airbags, 255/85/16 BFG ATs