One neat thing I've seen that doesn't get called out enough, is a high priority timer that has a slightly smaller period than your watchdog. When you let the watchdog, you pet this timer too. Then in the timer ISR, write out the trap frame to brain dead non volatile memory (we had battery backed SRAM, and then MRAM on newer boards). Then when the board reboots, and checks in, you can pull down what it was doing when the watchdog triggered.