Based on some early feedback and supporter questions, I have added, and am testing, a new feature in the firmware to allow the user's application to shut down power for a programmed amount of time to allow increased control over power management. For example, the ability to shut down the system at night or for a period between scheduled activities.
The new feature has been added to the watchdog control system as a special function. It consists of a new 16-bit register called WDPWROFF that specified the number of seconds (1-65535 - or up to about 18.2 hours) that power should be disabled if the watchdog system times out. To use the new feature, the user code simply writes the delay to WDPWROFF and then enables the watchdog timer (WDEN and WDCNT) and allows it to timeout. After the one minute Alert period, power will be disabled for the specified number of seconds. Setting WDPWROFF to 0 configures it with the default 10 second power-off delay for use with normal watchdog timeout functionality.
After testing I'll update the documentation on github.