I think it's unrealistic to presume that you can't and won't deviate from a route unless you're flying a commercial jetliner. Travel involves exploration. That said, if you're in the mountains, in the winter, well, hey, it's good to be careful, but you can't get every contigency.

That's why I think the single best thing to buy in this case is a 406Mhz PLB.

Dollar for dollar worth more than all the gear you could possibly pack. If I was driving in a remote area, with no cell service, no ham radio, nothing at all, $2,000 worth of suplies would not equal the simple effectiveness of a PLB saying "Here I Am Come Get Me, Please"

heck, a satphone rental isn't that expensive either.