Teams are required to be in team speak which riot modderators are also in. They are not allowed to mute their team speak at any time. On top of that they are required to have their cams on with it being recorded.
I don"t excactly know what a bootcamp entails, but on the topic I've heard Sliggy say, almost verbatim: "Coaches are is a seperate room, and the room with the players has cameras installed all over to ensure competetive integrity". If memory serves right, that is...
the most that riot does about this potential fraud is the mandate to have a referee in team's voice comms - would be very surprising if this is not done as minimum
otherwise it's just honesty and copium that teams have enough integrity