Important question: Is there a voice-over planned? That changes some considerations.
Generally:
Almost all of the instrumentation's voices are midrange. Harmonica, two guitars, solo. Especially if there's a voice-over, [ intellegibility issues] a good thing would be to move one of the guitar's ranges [I know there are some high notes on guit R...but open strings drone in midrange] upward...use a capo on 7th or 9th fret, for example...using alternative chord forms...or use a mando playing 2/4 with the clav. See if you can move the harp up an octave on the left. This opens space for voice w/o mid clutter.
The clave is a nice touch in the high end, but the timing with the guitar groove is a little off in places...it sounds like the guitars are rushing the pulse, if the clave is quantized to a midi grid; or the clave is working behind the pulse a lot. Not jiving perfectly, all the time.
The chord at 4 seconds...and then throughout the piece... is poorly defined; and the B in the melody there could use some movement up or down instead....a little too much constant major 3rd tonality for interest...and, over an ambiguous chord. Actually, I spend a little time on that top voice in the Piedmont picking guitar to get a little more motion and interest in it.
The solo....if it plays during voice: conflict of freq range. And I play in on mando, above vocal-speech range. If no voice, and generally, the reliance on triplet figures lends an out-of-character [folk/grass] bent. I'd prefer to hear mostly eighths...a little harder...and a more cogent melody: it sounds meandering, hunt and peck....I'd work out some concrete melodic finery in 8ths there. And I'd still use a mando...or a fiddle...to pop it out of the predominant frequence range.
The intro chord to the solo could use a substitution...a formal, notable introduction...setting up the entrance of the feature....like a following section does.
The echo on the drum seems excessive...not 'communicating' with the rest...
I don't know how far along you are with the project...but there's a lack of punch/ sparkle in the HF's of the recording. Like the guitars have dead strings..and they're recorded in an anechoic chamber.
Good luck with it!