It seems possible, although challenging; I'm curious for your take on this: 0. You run a large network with substantial hash power. 1. You submit a transactio

It seems possible, although challenging; I'm curious for your take on this: 0. You run a large network with substantial hash power. 1. You submit a transaction that is broadcast only to your own mempool and don't relay it outside of your network. 2. You attempt to include this output in some/most/all attempts. 3. You finally solve a block with this transaction and distribute it to the rest of the network. If this were happening, one way to surveil for it would be to keep track of every submitted transaction that a few nodes ever see. Is there a mining pool that is consistently mining huge fee transactions that were never present in your mempool?