Welcome, Kyle!
Although I am not not particularly knowledgeable about dulcimer history, the best source of information I know of on WV dulcimer history (and one with which you're likely familiar) is Gerry Milnes's Play of a Fiddle.
FOTMD member Kendra Ward's family has lived in Gallia County OH, an Ohio county bordering the river near Huntington, and she may be able to point you to some helpful source(s). On a related note, in Stories from the Anne Grimes Collection of American Folk Music, two southern Ohio makers are mentioned in a chapter that includes information on Kendra's father and grandmother-- the makers are a man named George Butcher who modeled his dulcimers after those of an earlier maker from Eno OH named John Wright.
Good luck and it's good to have you here, Kyle!
updated by @robin-thompson: 02/16/16 05:38:45AM