If I understand correctly, stream isolation will route different connections through different circuits. If you’re doing two different things of a sensitive nature, open different browsers and applications, use random user-induced delays in your actions/responses and PGP-encrypt everything. And listen to what the TOR project says about the mitigations. I have some reading to do myself I guess

This attack has been known for years now. And tor is simply not able to defend against it without a complete redesign.

What else you going to use?