You might want to check out a Mountain Cur, it’d be hard to find a better athlete, very intelligent, quite and tough as nails.
Both mine were about 30 lbs. Mine would tree naturally coon, squirrel as good as any Walker I’ve owned, and one would run done and flat whip every coyote that he got wind of too. Stayed and kennel’d as good as I’ve owned.
Might or might not be a tad bigger than you were looking for, not cheap but I wished I had one now.
