I really got it messed up!! I had jumped to the conclusion the discussion was about "White Latin Cross" flags. Thanks for the clarification!
The Magruder Flags sound like a variation of South Carolina flags presented in Glenn Dedmondt's "The Flags of Civil War South Carolina" (Pelican Publishing, 2000) on pages 31-32, and 124. Glenn identified these as "Mercury pattern" flags in honor of a "Charleston Mercury" newspaper proposal in early 1862. Is there a connection to the Magruder flags?
I would love to see some sketches attached to these discussions! The variation in Confederate unit colors is endlessly fascinating. And I hope the Devereaux FOTC website can be restored soon!
Hugh