This is something I've wondered about but never tried. In googling I see it has been done. I think fret adjustment is over emphasized on classic guitars, tiny fret adjustments on electric guitars are more nessesary. With a traditional guitar, a top with a lot of flex buzzes more than one with less flex. It is
widely acknowledged that Flamenco guitars buzz more . Yes, it would take some trial and error to find the best location for good balance and there would be some volumn decrease. But most play without an audience. I suggest that for those who own inexpensive Classic guitars the change could make for a more pleasant experience. All bowed instruments have sound posts and adjusting them has to be done with the
"f holes" as only access. With a guitar it would be easy to reach in. Certainly anyone trying post in guitar needs to understand that it must be just tight enough to stand and the job will take lots of trial and error.