My sister lived in Wingellina[1][2], Western Australia which was a 6 hour drive on unpaved, 4WD required track from Alice Springs. That's close to one of the most difficult, isolated places to get to in Australia, but even there isn't a week on Camels. Maybe going further west into the Great Sandy Desert might get close (although you get close to small townships in WA if you go too far).
The Empty Quarter has low population density but is smaller than isolated areas in Australia.
There are probably places in Siberia and Canada that are fairly isolated too.
I agree that there are more isolated islands. The Pitcairn Islands is the most obvious case.
[1] https://maps.app.goo.gl/Q2wL9KCa9aXht3YS9
[2] https://en.wikipedia.org/wiki/Wingellina,_Western_Australia
