Bunker creation would be cool. I'd just reduce their defensive effects. Also, setting up "pillbox" not "PILLBOX" positions across the front would be realisitic. Setting them to just above BUNKER defensive value. Night movement disruption is still a problem for deployed mechanized units. I'd set it fairly low though.
You could drop the day/night Delta values in order to give it a more realistic time aspect. Foot speed should be 5. I'd up the mine prob to make mining a more realistic defensive strategy. And so on..
The mines were never that extensive and in the early 80s they were dismantled.