i can hear what you're saying about the vocals not meshing in with the guitar.
to me the vocals sound louder than the background music, and that is what puts it too far out front.
i wonder if you do another mix, but this time set your volume of the music, then set the vocals at the same volume (which will be a bit inaudible)....then finely split the music sections only where there is vocals and lower the music volume, only at that section, to make the vocal volume appear clearer,
like a "ducking" effect, then when the vocals leave, the music doesnt seem so far back and the volume change is less noticeable.
also there is a flangy-like effect on the acoustic and the vocal sounds spotlessly clean, which also seperates the two, maybe try cleaning up the guitar or ..either... add some of the same effect to the vocal to blend them together more.
when the bass and percussion /drums come in could be something to glue the vocals too...hmmm?
interesting post.just a thought...
if it's not happening in the room, it ain't gonna happen on tape.-HG