one thing I've read in other posts is that the new content doesn't actually show up in the game unless you go into truly unexplored areas.

Just pushing a bit past your previous edge of exploration isn't enough as the terrain generator does about 500 meters (how do you messure that anyway?) past the edge of your minimap.

I've dropped a marker on my map and walked out just 30 meters (edge of workbench radius) and dropped another marker. It covers more distance on the map than I expected so getting a half klick past the edge of my explored area is going to be a hike and a half.