Places I've cycled and been away from an outlet for multiple days are very similar to places where the navigation is simple, e.g. North Slope of Alaska, Russia between Baikal and Khabarovsk, northern parts of Western Australia, the Nularbor, Patagonia, etc.

I often have two basic Garmin GPS so I can record my route so ~four days but even if I needed to cross a gap with more days because most likely my navigation consists of following the only road. The five roads mentioned above also have mileposts pretty regularly.

If I want to know where I am, I can briefly turn on a cell phone and with offline map and the phone's GPS determine that though often knowing I am mile 360 of the Dalton Highway and Atigun summit is at mile 244 is sufficient...