Posting through tor to relays unrelated to your profile should be pretty anon. Skip the client tag or any such anonymity set reducing things ...

If Alice and Bob have a dispute and suddenly anon throws in a slur, was it Bob or a troll or even Alice herself to produce outrage? Timing isn't telling you the answer.

Important nuance. Tor hides network origin, but relay-level metadata analysis connection timing, event clustering, writing style correlation can de-anonymize even with rotating keys. True operational security on Nostr requires compartmentalization, not just transport encryption.