I doubt that anybody ever pronounced the u in 'Suwannee.'

It's true that the word 'plantation' occurs in the first verse, but the other verses refer to a little farm and a little hut. So the jury is out on Foster's real view of life on the Suwannee.
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Thread drift - Q, did you see that I wrote music to the minstrel song from the Library of Congress that you posted earlier? The thread is called 'a humorous song folk-processed.' The thread has a link you can click and hear how the music goes.

I'm being attacked because 'I didn't need to write it.' As if there's a law that says only one version of a theme is allowed. (Actually they're incensed because the song praises the banjo.)
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Back to the Suwannee River: I've been studying the map of Florida. I see no reason why they couldn't have been playing banjos on the Suwannee, especially where it meets the Gulf of Mexico and one could make a living fishing.

To this day, much of the land inland from there is uninhabited wetland.