Don't have to be remote at all. My go-to place is 1km from the nearest big road and 5km from my city central (small city).
Basically it's a narrow dirt road with a few houses here and there.
Afaik, it's enough that it doesn't have a set biome. To my knowledge there isn't any map that you can check.
From my experience if Google won't bother driving there with their photo car it's remote enough. You could try checking your area in google street view. My place i bet has a street view so it doesn't necessarily tell everything, but if there isn't a street view available then I bet it's remote enough.
Map wise I'm thinking they use Open Street Maps definitions, so that might show you the biomes and stuff. Not entirely sure about that though, just some theory i read a while ago.
