The B3 supporting the tune is how I (think) I would approach this tune. You seem to be thinking simple, which I think is right, but the 2 note "chords" and no single articulated notes sound like you are wandering. I suggest full chords and single notes. Precise is tough but it's essential. Love Keb Mo, by the way. He may be more difficult to play than you realize -maybe Jimmy Reed would be easier. Just my suggestions.
You are staying on the same chord through the entire tune. You've got to change what you are playing to go along with the chord changes. Single notes that move through the rest of the chord progression would work.
The actual chords available on the harp are limited, so single note playing is often necessary to move through the chord changes of a tune effectively. Just repeating a single chord lick through the entire tune doesn't cut it--it is a nice lick, but it becomes repetitious and doesn't fit every place you are putting it.
Thanks for the comments. As you can tell I am a novice and don't really understand the technicalities you mentioned. What are these other chords you speak of ? It sounds like different chords to me.
