I don't mean any disrespect but let me offer you a friendly advice -- don't do it to yourself. I think you would have a very hard time finding someone who would recommend implementing a solution that involves mixed versions. If you run into issues, it would be hell trying to unscramble that egg.
On top of that, Cassandra 3.0.9 is an ancient version released 4 years ago (September 2016). There are several pages of fixes deployed since then. So in the nicest possible way, what you're planning to do is not a good idea. I personally wouldn't do it. Cheers!
