But there would only be one less whisper to set up as there are channels...if there are 2 multicrewed tanks then there are only 2 whispers for a person to set up as all loose tankers are together in one channel talking to eachother as are those in a multicrewed tank.
eg. Painless's multicrew tank would need a whisper to 1) Friar's multicrew tank channel and 2) the loose tankers channel
Friar's multicrew tank would need a whisper to 1) Painless's multicrew tank channel and 2) the loose tankers channel
One person in the loose tankers channel would need a whisper to 1) Painless's multicrew tank channel and 2) Friar's multicrew tank channel
Also, anyone changing roles in a multicrew tank can still be the comms person in that tank to the other channels, that doesn't need to change.