For your next project, since you're already set up for it. Convert the remote XBee into an end device, put it to sleep for long periods (minutes) and have it wake up and send the reading.
Advantage: eats very little power, so the XBee can run off a battery and a little solar charger and be placed anywhere.
Disadvantage: doesn't do store forward so it cannot support devices further away than it is.
Devices like this can control solar automatic gates that are at the end of a dirt road with no power available.
XBees are cool.