G
What happens after you call py.go_to_sleep(), is the Pytrack coprocessor cuts off the supply power to the microcontroller. This is the lowest power sleep state available. On the accelerometer wake, the coprocossor switches the power back on, meaning the Gpy will boot up as if it was just plugged in (starting with boot.py and continuing in main.py). If you have a pytrack 1, you do not have to use the workaround provided in the link I posted.
The suggestion to wait 10 minutes is because sometimes you have to wait for traffic lights and such, where you do not want to turn off the tracker. I would take the inactivity interrupt (which follows the activity interrupt, when the movement is on the falling edge) from the accelerometer, and note down the time. Then, in the main loop check that time against the current time and see if the 10 minutes have passed. If so, go to sleep and make it wake on accelerometer. You'll have to set the sensitivity just correct that it does not wake up on small movements of entering and exiting the caravan, but that it does trigger on driving it on the road I presume.