Why would you need to download the blockchain over Tor? There are many people downloading the blockchain and that in itself does not incriminate you. It seems sufficient to only send out transactions using Tor.
A relatively tiny number of people will ever download the blockchain, a relatively tiny number of people use Tor, how many bits of information does a state level adversary need to deanonymize someone?
I'm interested too, hope the OP or someone can answer. Also, why does the transaction itself need to be sent over tor? I thought Monero's feature is that you can't tell from a transaction who the recipient is (ring transactions or something?) but maybe I don't understand the end-to-end flow and the math well. What is incriminating when you publish a transaction without tor?