I wonder how their upkeep and bulging expense (especially across difficult terrain) compares to that of the small nuclear power plant described here. We could determine the distance when the HVDC line still makes more sense.

For true "wilderness" your total addressable market is like a million people. Sweden and Norway have abundant hydro power so they actually export power from north to south. So reduce that to tens of thousands.

For southern scandinavia it is already connected through HVDC to Central Europe and more are being built.

https://en.wikipedia.org/wiki/Circumpolar_peoples

https://en.wikipedia.org/wiki/Arctic_Circle

Nobody knows what this reactor is going to cost yet, the first one has not been completed ..