I have a hand crank flashlight that doesn't need batteries. It also has attachments for charging cell phones.
A Sat-phone would make being lost in the wilderness a little less distressing.
And they can be rented.
Which brings us to EPIRBs (Emergency Position Indicating Radio Beacons).
Pretty sure you can rent these as well.
Oh and make sure you tell someone where you're going and when to expect you back and what to do if you don't show up.