Lon Abernathy was found (under various name & alternate spelling variations) on several Federal Census Records in Ballard and McCracken County KY (1900, 1910, 1920 & 1930). Alas, the occupations given for your Great-Great-Grandfather Lon range rather widely: laborer (aged almost 21), Telephone Exchange Operator (age 32), Grocery Merchant (age 41), and Truck Driver, Ice Factory (age 50). No hint at all on census records of ownership of a tobacco plantation or of farming as a primary occupation. I _think_ I have tentatively id'd his parents and/or grandparents, and it could well be that they owned reasonably decent floodplain farmland in Ballard County on which the family may have raised several tobacco crops in various years, but I have yet to find a record of the amount of acerage or of the land being specifically identified as a 'tobacco plantation'. I do not even know for sure that they owned the land outright, with a mortage, or merely rented it. You will need to concentrate your research on agricultural and land records of the area in and around Woodville in those two counties to see what you can find out.
If I'm right (but I've been sadly wrong a few times before) your Abernathy Great-Great-Great-Grandfather may have been born in Mississippi from a branch of a hard-working family that arrived in the colonies before the Revolution and has prospered reasonably well in the years since, except for those who lost everything in that 1860's war. At this point in a slightly cursory investigation, I'm certainly not prepared to definitively state whether or not the family was a Scots or Irish emmigrant family. I suspect the former, but there were both in several of the colonies 'way back then and they've inter-mingled extensively in almost every one of the many states they are presently found in. Abernethy/Abernathy/Bernethy is not exactly an easy surname to investigate.
According to census records Ella's sisters were Myrtle J. (born cir 1901 and probably married in Ballard County between 1920 & 1930) and Duella Inez, born cir 1904 and still single on the 1930 McCracken census. I didn't have any luck in finding their marriages in KY records, but you might, if you dig carefully & deeply enough.