a 12V air conditioner for van with large cooling capacity will definitely cost too much energy, therefore an auxiliary battery will be needed if you buy a 12V system.
Maybe you could have a look at this one?
BTW, do contact the sales to confirm the following information:
1. its cooling capacity
2. its exact application, for what kind of vans?
3. whether the heating function is available?
4. its energy comsumption
5. a littble bit info. on its compressor.