How much "chatter" do you really need to coordinate something like this?
If it is a small group of just half a dozen people you should be pretty much invisible if you act a bit clever. Coordination can be done via throw away sim cards and personal meetings so you don't really need to communicate that much.
Hacker News should automatically add the size in MB for each submission. This would a) act as a warning for mobile users (the BBC article about dark matter on the front page at the moment killed chrome on my phone because it has too many images) and b) acts as a wall of shame.
If it is a small group of just half a dozen people you should be pretty much invisible if you act a bit clever. Coordination can be done via throw away sim cards and personal meetings so you don't really need to communicate that much.