Haven't been to the Ozarks personally but large black cats are one of those things I keep seeing reports of from all over, and it's not just the US either. We get them in Essex fairly regularly, the so-called "British Big Cats" - farmers losing livestock, solid pawprint casts, occasional decent photos. The pattern of sightings is always similar regardless of location. Solitary, mostly nocturnal, people catching glimpses near treelines or field edges.
What I'd want to know is the rough size estimate compared to something nearby for scale, and whether the movement struck you as unusual. Domestic cats move differently to big cats even at a distance, there's a weight to it. If anyone has photos or even rough sketches of what they saw I think it'd be worth putting together a comparison. These sightings deserve proper documentation rather than just getting laughed off. What time of day was the sighting and what area exactly?