I am using monit in embedded devices, very successfully for last 5
years or so.
I have patched in functionality to help me handle watchdog devices.
Since monit is used for system and application supervision, it was
natural to have it also handle watchdog.
If this support is of wider interest, I can send in a patch.
Implementation adds configuration parameters that point
out /dev/watchdog file to be handled, and how often to do it.