The main benefit I'd see to the last option is that it would also cover passing a "filter" option for tarfile.TarFile.add(). Dropping down to the lower level API for that isn't *hard*, it's just a bit fiddly (note: currently untested example code):

   sdist = tarfile.open(sdist_path, "w:gz", format=tarfile.PAX_FORMAT)
   sdist.add(os.getcwd(), arcname=sdist_subdir, filter=_exclude_hidden_and_special_files)