If you have a 'grep' utility, you can filter out most of the known tags by piping through "grep 0x", but exiftool doesn't have this feature on its own.

Exiftool accepts the two EXIF:Copyright two fields separated by a newline, which can be inserted using various techniques discussed here in the past. The newline is converted to a null internally.

If you need help with the newline, let me know and I'll look up the post for you.

- Phil