Decouple the environmental controls and electrical subsystem from the engine by using a separate electricity generator with a separate fuel supply. Use deep-cycle marine batteries as a buffer, and have the generator turn on to top them off when they get below a threshold. Meter the power usage for the generator, and charge for distance travelled and by power used.
A lot of owner-operator truckers have discrete electricity generators, because running the engine just for HVAC and electric power causes unnecessary maintenance costs. There are even truck stops that pipe in electricity, HVAC, and video channels through an umbilical that hangs down to one of the windows.
A miniaturized RV that is basically a stripped-down mobile motel room will also have a decent post-fleet-vehicle secondary market, as people buy them to live in full-time, or use more like a traditional RV, excepting that it can fit into a van-sized parking space.
Also, I'd just use blackout curtains or aluminum shutters instead of the electrochromic glass, and use a removable or retractable privacy barrier between the driver compartment and the private space. I'd rather use simple and reliable tech for simple requirements.