I would like to suggest that an Officer can operate as a mobile spawn point, selectable from the respawn order of battle, similar to naval respawn points. But with a limited number of reinforcements available at each reinforcement cycle.
I suggest the following limitations:
50m from HQ - 4 units allowed to spawn, 100m - 3 units, 150m+ - 2 units
Optionally, require the officer to be holding his lantern and have line of sight to the HQ.