SG57
Former Vendor
Check out Dashboard for Tesla, it's the better app for your Tesla with all the functionality as the official and then some extra features and more on the way.Oh. It's not available for Android. :-/
Camper Mode is one of the additional features currently available, it allows you to keep the HVAC system on indefinitely, as well as automatically turn off if the car battery drops below your desired percent.
Disclaimer: I'm the developer.