Terrain mod question

[Blackcloud6]

I've set up and played a turn of 1967: SoI Scenario 18.  This is a pursuit scenario and thus movement is crucial.  The scenario converts all roads to tracks, and all towns to Sand Dunes.  This results in all the tracks being broken up by the dunes and therefor slows movement considerably.  But I wonder if the intent was to have the tracks go through the dunes.  By PG concepts there are no roads in towns, so I started playing that the tracks do not extend to the dune hexes.  Also, to back that up, I've always played that a conversion completely changes that hex to the converted terrain and none of the printed terrain is carried over to the new hex unless the scenario says so such as: "treat all town hexes as sand downs, but the printed road exists in the hex."  The scenario does not say this so I am assuming the towns are dunes and that the road/track does not exist in those hexes.  is that how you would play?  Thoughts?