I think the car batteries would be great in a van, and from looking at the Tesla frame, they're flat(ter). Then you could charge at the recharging points. The 'free' ones are generally if you sign up for the program when you buy the car. I think Teslas is about $1000 option (don't quote me on the price.- I may be way off). THEN you get the recharges free. But from what I've read, a charge is only a couple of dollars.
Perhaps one of our electrical,experts here could estimate how long one would last before needing recharged, under a typical dweller's use.