In addition, you mentioned pensions. Again, this varied from State to State, but I don't think that any former Confederate State paid pensions for local service (i.e. State reserves, home guard, etc.) The UCV had lobbied against giving pensions for that sort of service.

The thought had occurred to me that these workers may have been contract workers to the Confederate Navy, but again, I don't think that would have qualified them for pensions.

You may want to look at, and compare, the units from the Richmond Arsenal and similar units. You may find a clue as to their status.