Almost certainly the car will power down if the battery SOC gets too low. Even in neutral.
Someone should test this while watching.
(You sound like a good candidate.).
Watch the car and turn it off 15 minutes after your last battery bar goes dark if the car does not shut itself off.
Pretty sure it will protect the HV battery.
(It may not protect the 12 volt battery, but there is a very good chance everything shuts off.)