If you are going to the Library of Congress on Wednesday, you might want to peruse my regimental history of the 31st Georgia Infantry, of Lawton's Brigade. I've got some Fredericksburg material that might interest you.
Keep us posted should you stumble on that elusive 13th Georgia publication the LOC once had in its holdings. A number of us have made inquiries for it, but with no success. I suspect it was privately published in a limited run, perhaps for family consumption. None of the repositories here in Georgia has it.
Sincerely,
Greg