You can buy sick powerbanks and portable power packs now. Have a look on Amazon. No need for built in electrics or even a leisure batery for most people who only do short trips. Charge up your power pack and put it in the van when you head out.
Vw van prices are high at the moment with COVID. I know it’s been mentioned further up the thread. Depending on budget you could look at the likes of a ex AA or RAC van. A friend on mine has a ex RAC van. Another friend got offered a T5.1 that had a front end crash so bought it cheap and put a new front end on.