First, let me state not only do they still get most of the coverage even today, but that the ANV got officially got preferential treatment during the war. That is confimed by a statement from James A. Seddon who wrote as Secretary of War in late 1863, "I have directed that if ouir supplies are to be limited to allow due provision of all armies, those serving in the Northern Virginia and mountainous district [Shenandoah], should be preferred!" From page 78, Cadet Gray and Butternut Brown: Notes on Confederate Uniforms by Thomas M. Arliskas. Now, onto your question. There is an "officer's battle shirt" worn by Frederick William Bush of the 1st Arkansas Infantry, who never rose above the rank of sergeant (See Page 9 of the aforementioned book) who was in the ANV for a short time. However, I am sure you would be more happy to see the shell jacket worn by Captain Alcibiades DeBlanc of the 8th LA Infantry, ANV. That wiould be on page 67 of "Potraits of Conflict: A Photographic History of Louisiana in the Civil War" by Bobby Roberts and Carl Moneyhon. For a shell jacket with a style similar to Buckner's plated fatigue coat that you mention only shorter, look at Pages 142 - 147 of Volume IV of The Confederate General series edited by William C. Davis. You will see five pictures at different angles of the late war uniform of General William Mahione of the ANV. This does not technically count as an answer to your query, but on Page 90 of the same volume, Longstreet is wearing a REAL short double breasted from. It almost could be considered a sack coat.

Yes, a frock coat, even an unlined one, is extremely heavy and hot in the heat of Gettysburg, etc., but it was regulation. Stating that, I do alsio see many officers in single breasted frocks so it seems they could vary a bit as the shorter coats above seem to prove.

I hope this helps.