The trouble is that there is no such thing as “dead ground” in the absolute sense of being a specific place.
To add to what I said earlier about the terrain granularity matching the troop scale, let me make the point that it should match the scale of command decision as well. By that I mean, if as a player in a Quatre Bras game I am making decisions in the roles of Ney and/or his divisional commanders, then those decisions should be based on factors those generals could have been aware of. If the dead ground is created by a ridge/gully significant enough for them to see from their vantage points, the ridge should be on the table. If it’s one of those more subtle undulations whose effect only becomes apparent when the lance pennons emerge out of it from a particular direction, then perhaps it should be left to the dice.