That's damn near perfect! Small in territory and population; only the US can conceivably intervene, but they would have to deal with Cuba too, which they probably won't be up for; and while it's not exactly desolate, it would still be isolated from everyone except their Cuban benefactor. And the rump state, already small as it is, will shrink even more as the hardliners die out.I was about to suggest Ernst Thälmann Island too.
When I read about the SADR I assumed it was showing the population of the controlled territory only, not claimed. Though yeah, that does make more sense.IIRC, most of the people in West Sahara are Moroccan settlers who live in the Moroccan-occupied areas of the region, so there's that.
This would not be a rump state, the Nazis would just be taking a bit of territory they occupied and propping it up into something different for marginal legitimacy.Edward VIII does not make it out of Paris and the Nazis send him to Jersey or Guernsey and call him reinstated King or something.