Hi, Krys! I, too, am a direct descendent of William C Beal via his son, my g-g-grandfather Enoch Moore, my g-grandfather Charley, grandfather Roy and father Charles. I have also ploughed face-first into the stone wall that is destroyed records.
The closest I have come is locating one Thomas Beal in the 1820 Giles Co, Tennessee census with 1 male child under 10 at the time. If this is the correct Thomas and the record is accurate, this would be William C as he would only have been an 8 y/o at the time. Thomas was in the Over 45 category while his wife was in the Over 45 category as well. I have never been able to confirm his wife's name. He appears again in the 1830 Giles Co, TN census with the appropriate age, 50-59. However, she appears to have been miscategorized in the 40-49 range. I believe he appears as Thomas Beal Sr.
So far, though, everything points to the same Thomas and Lydia from Chatham County, NC of which Meganne Woodland speaks. If the age ranges for Thomas in the 1820 and 1830 are correct, this puts his DOB somewhere between 1770 and 1780. Hopefully, we can narrow it down from here.