Hi there philgeek
I have also tried the Mkrfox1200 in Lowpower deepspleep. (The board has its own way of behaving).
I need a board for long life. As a test I have put the board in deep sleep for intervals with a tmp36 temp measure sensor. I have measured the voltage between vcc / ground and the current used by the sensor. When the board changed to sleeping mode the values did not change.
I think thats not good for a long battery life – did you find a way to make the board “total sleep” .