I prefer that my document mutexes present in the operating system’s standard temporary file directory, rather than alongside the original document. It tends to clutter things there. Is there a setting for this?
There is no setting for this.
… and that doesn’t make sense anyway. The idea of lock files is inform another LibreOffice program, running on a different session/system, that the file is locked by someone. So where should that other program look for the lock file? How could it know who opened the file to try to look into that specific temp directory; and how would it access it there?