Rather than setting the radio for TX then back to standby specifically for the purpose of measuring the battery, I was thinking of taking said measurement as part of a regular transmission.
In my applicaiton, when the moteino exists listenmode because an update is requested from Gateway, the response is given using sendWithRetry(). If battery measurement could be taken as part of sendWithRetry, stored, and returned to gateway with the NEXT requested update... the gateway would always be behind one update on battery level, but it would still show the trend, and it would reduce overhead.
Also even though the gateway is one update delayed, the node locally is not, and can use it's knowledge of the battery level to make intelligent decisions about power management... whatever that may mean.