Hijacking the vehicle heating and cooling. Looking for advice.

I am buying an EV van (VW [ID Buzz](http://ID.Buzz) Cargo) and the biggest issue I have with using it for long trips is going to be heating and cooling the vehicle when I'm not driving (especially if I need to leave my dog in the car). I am aware of 12v/24v split systems but the van I'm buying already has a state-of-the-art climate control system built in and a massive battery. Ignoring the drain and extra cycling of the main battery, has anybody had success or issues using the vehicle climate system instead of an aftermarket system in an EV?

Note, I did a calculation of the power requirements based on the vehicle and battery specs and a full battery should be able the run the AC constantly for \~40 hours or the heat pump for \~60 hours. Obviously I'd want to keep some power in reserve for driving to a charging point but in theory there's enough power there. My main worry is whether this could cause overheating of the main battery since the vehicle isn't moving and there's no passive cooling from airflow.

I should also add the IDBuzz doesn't appear to allow this by default. It switches off everything if no people are detected in the front seats. There are workarounds for this but it's still worth mentioning.