Except for the new thematic material at the end, your use of rhythmic material is good,
especially here:
where you mixed your A and B.
If you want a bass clarinet player to play the piece I'd suggest making it longer.
That's a rare instrument (at least here) and I assume that when you find a player he'll expect a longer more developed piece.
The abrupt change of the harmonic rhythm at the end feels awkward, especially since the other voices drop out. i - iv - V isn't really that much of a music theory hack; it's decently standard, but makes for a great way to add a three chord (12-bar) harmonic structure instead of the typical 4 chord. I'm curious as to what you find "neoclassical" about this necessarily.