I won't claim to be an expert, but given that most similar implementations to what you describe do use a switch, my guess is there's no software way. I think you need a switch or jumpers.
Second, again I'm not an expert, but I think it's relatively likely that BLE communication will handle turning off the transmitter for you. I mean it is Bluetooth Low Energy, after all. I'm pretty sure it needs some amount of two way communication to ensure data integrity, but that it will keep that to a very nice minimum for you.
--Donnie