What I want is to specify that for a directory, every file creation/modification within said directory will be checked by the kernel and if the filename has unsupported characters the offending process will be given a "permission denied" error.
I was thinking about writing a fuse-driver that rejects non-compliant filenames. But that does not seem practical.
I am not looking for solutions that recommend things like a cronjob or inotify that clean up unwanted characters after-the fact. I'm looking for something that is preemptively preventative.