I thought that if anyone knew, you would. I can imagine the possibility of tying a black flag to their saddle or to their sleeve but I would think that, in a "black flag situation," you would want both hands free. I'm sorry that no regular flag is known to have survived from these commands.
If they were known to exist, I wouldn't imagine that they would survive the wrath of reconstruction. Even when Grover Cleveland suggested returning the battle flags, the GAR veterans said burning them would be more appropriate.
Thank you very much.