I would go with 4 wheels, not 3 wheels. At some time someone will have an accident. A vehicle with 4 wheels is less likely to roll over. Some injuries occur due to roll over.
On your video you mentioned solar panels on a trailer. Don't put them on a trailer. Put them on the main vehicle.
You could make a single seat model, and a twin seat model, and even a model with more seats. They could be used as environmentally friendly taxis.
Make heating and air conditioning optional. Ventilation is important.