Can Kalonji get his Sons of Confederacy Membership? Maybe DNA can help!

I’ve never participated in a Carnival of Genealogy before, but I could not pass up the topic of this next round because it was extremely apropos.
The question: Do you have a family mystery that might be solved by DNA
The answer: yes, i think so! but, I’m not sure. I have some theories to test.
My husband want his Sons of the Confederacy membership. He is a McClellan from Talladega, Alabama. Here are the facts:
The Black McClellans

• There is an oral history that his black McClellan family bears resemblance to the white McClellan families in the area. I need to double-check this with his paternal grandmother Frances, but that is what he tells me.
• His great-grandfather is named Champ McClellan and was born about 1887 or so in Talladega, Alabama. Champ is Frances’ father.
• Champ’s mother’s name was Fannie McClellan. Though the 1930 census says she is widowed, her death certificate shows that her mother’s name was Rebecca McClellan. Fannie married later in life after having two children, but the last names of both her children, Champ and his brother, was also McClellan, so this leads me to believe she either married an unknown McClellan, or she had her children out of wed-lock.
• Champ was very light-skinned and his death certificate does not list his father. Census records list him as mulatto. Mama Frances says he was “bright” and very near white. She said her older sisters, his first two children, were also very “bright.” She said he never talked about his father, but she too wondered if his father was white.
• I cannot say CONCLUSIVELY that I’ve found Fannie in any census prior to 1900, but my best guess based on Champ’s age is that she was born somewhere around 1860-1865. Her death certificate when she passed in 1953 says she was 77, but that would make her only 11 years older than Champ (who’s age is more accounted for than hers).
• I did find a Fanny McClellan in the 1870 census, mulatto, listed as being 25 years old, thus born around 1855. Her age is not quite on par with what I think is Champ’s mother age, but I can’t rule her out either.
• I have not found a Rebecca McClellan that even looks like a close match to be Champ’s grandmother.  Update on 11/3 – see the last bullet point in the White McClellan’s section.

The White McClellans

• The white McClellan family in the area are the family and descendants of General William Blount McClellan.
• General McClellan was a large slaveholder – in 1860 he had 15 slave houses and real estate value of $15,000.
• General McClellan served during the Civil War and was a Confederate soldier.
• General William Blount McClellan had sixteen children, including a son named Augustus R. McClellan, born in 1842, did in 1875.
• Augustus R. McClellan lives next to the above mentioned Fanny from the 1870 census – she lives right next door.
• Augusts McClellan’s census record for 1870 shows a 2 year old son named Champness (thus born about 1868). I have so far found no further information about Champness McClellan.
• With the assistance of a lady whose husband is also a McClellan descendant, she pointed me towards this 1880 census of the General William B. McClellan household in which there is a 45 year old black woman named Rebecca with a 14 year old daughter named  Fanny. Also, in the house is an 8 year old black boy named Chap (could be a mistake for Champ).  Could this be Kalonji’s Fanny & Rebecca? Is that Chap a brother of Fanny’s?

All this combined really leads me to believe that I have a plausible theory, that Kalonji’s great-grandfather Champ was fathered by one of these white McClellan men.  Kalonji occasionally grows red hairs (as does his father) and the white McClellan’s are of Scottish descent. Of course, this may not be the case, but our first set of DNA tests that we will do will be to try and solve this.
With help from above-mentioned researcher, I am constructing the white McClellan family tree.  If I can find a son of a son of a son, etc. on down the line to test (or two), it would help me either way. If a yDNA lineage test shows a match, then we know it to be true! If the test does not show a match, at this point, my next plausible suspect is a member of the Plowman family.   Three of Willam B.’s daughters married three Plowman brothers – so with Plowman’s in the household…  Of course, that may not yield a match either. But, we are certainly going to try!
I’m confident I can track down someone, the challenge will be to see if any of them have done a yDNA test or would be willing to do one. Some may not be willing to do it as they may not want the association, but really – we know this kind of situation happened all the time! I hope I can find someone who is willing.So, that is my objective. I look forward to taking this on over the next year and seeing what we can find out!