I am in Brooklyn too, although looking for a short bus as a vehicle, not planning to live in it, as there are five in our family and while we would live in a bus we are stuck part time in nyc as we have split custody of my stepsons and I have no interest in street parking anything over 23 feet here. When they are 18 in 7 years we’re gone!
I’m not far along enough to offer much guidance, but do believe it is legal to live in your vehicle in nyc. People convert for registration to ‘Home on Wheels’. And yes, don’t buy anything around here/in the northeast unless someone just brought it here from elsewhere.