Kind of thought about how conflict geography would emphasize the hard/soft AH divide. See, Smithtown's Republic of Oran is thematically similar to Rhodesia, but its geography (and also opponent) is completely different. Instead of a wide open brush dominated by small units, you'd have a cramped mountain and trench line that would become an attritional grindfest.
Now Smithtown was an ultra-soft AH, and the macro-conflict wasn't the point. But I'm thinking in how a harder AH would go for the more plausible "attrition line", while a softer one would have the Force de Feu jumping around in helicopters against guerillas to emphasize the metaphor.
There's definitely room for smaller units to still do those types of tactics. The DPRK has plans for infiltration of the RoK by air and sea. The An-2 is difficult for radar to detect because it is mostly made of wood and canvas, and the DPRK has also illegally acquired civilian MD-500 helicopters that are similar to military models operated by RoK and allied forces. There have also been several instances of DPRK submarines landing infiltrators along the coasts of the RoK.
Even larger units can pull it off. Some of the largest amphibious operations in history were conducted in Greece and Korea and some large airborne assaults have occurred in Greece and Afghanistan. A Korean conflict would be heavily mechanized despite the geography being poorly suited for it.