John Turnbull was a 49 year old labourer from the county/parish of Orleans https://www.fold3.com/image/41728561?terms=john%20turnbull , no apparent military service.
William K Penny is the only person named Penny with any commissioned rank in Louisiana service. He appears to have been a member of Tyrian Lodge No. 206, http://library.la-mason.com/PastProceedings/1870/1877-1878.pdf .
I had no luck finding Miss M. R. Pickings.
Unfortunately the census records for Tensas parish are not well completed.
Will keep searching as I like a bit of problem solving.
My gut feeling is that the Waterproof Guards were a small unit which were absorbed into the Concordia Rifles, it might be possible to prove this if we can find a muster roll for the Concordia Rifles and check the names against the census results from Tensas Parish.