Tesla's unlike our prior 2014 Nissan Leaf, like to be plugged in, and will intelligently manage the charging.
The Nissan Leaf we made the mistake of leaving plugged in while on a long trip, and came back to a dead 12V battery. The 12V was only charged when the vehicle was turned "on", and was used for the charging signal communication.....
Tesla is a LOT smarter than that, and it just "works" the way it should. Leave it plugged in, maybe set the charge level down to 80% instead of the normal 90%, it will manage charging the 12V battery as needed, and keep everything clean.
-Harry