For scenarios with multiple platoons, the following rules can be used.  

 Each platoon/battery/troop (4-8 tanks) will have a PL. Communications within 
the platoons will work as outlined in the Rumble Rules.  Communication between 
the platoons will be handled as follows:
 The PL's can send Radio1 & Radio2 messages to each other freely.  They can 
also send one Radio1 message to a non-PL tank in another platoon if it is in 
LOS. They can send a Radio3 message to another PL in place of the Radio3 
message to one of their own platoon tanks.
 Non-PL tanks can send Radio1/Radio3 messages to tanks in another platoon in 
place of the standard Radio1/Radio3 and only if they have LOS to that tank.