Never been to the Ozarks myself but we've got something vaguely similar going on near some of the forestry up in Aberdeenshire - that low, almost melodic howling that doesn't quite match anything you'd expect. People up here blame foxes but foxes don't sustain a note like that.
What's catching my attention with your post is the "definitely isn't a coyote" bit. You clearly know the area and you know what coyotes sound like, so I'd take your instinct seriously. There are a few accounts from that region going back decades that mention large unidentified animals, some researchers think theres a remnant population of something bigger than coyotes moving through those hollows.
Has anyone managed to get a recording? Even a rough phone recording would help narrow things down. Would love to hear what others in that area are picking up.