Gibb, I agree with your analysis but would add that, while anything is possible, if "Shannondore" was sung, "Shenandoah" was almost certainly intended.

From me on another thread a dozen years ago:

"In 1716 ... the colorful deputy governor of Virginia Colony, Alexander Spotswood, explored ... the Valley with his small but well-provisioned band of adventurers. They forded the South Fork of the Shenandoah River, which he named the Euphrates." -- Official website of the Town of Stanley, VA.

"O Yoofrateez,
I long to hear you!"

Further investigation shows that by 1746, the Indian name "Shannandore" (so spelled) for the river had come to be used by white settlers. Excellent choice.

....

I've looked further into the alleged existence of an early printed version of Whall's text. It seems to be unfindable.

I suspect that Whall's belief that the song came from a book was just a trick of memory.

But his assertion that he'd heard it in the 1850s remains presumably accurate.

PS: No one should get the idea that the "Yoofrateez" version was the "original." I simply made it up for our entertainment.