Following your responses, I looks like you want the space and features of at least 200 sq ft of house, which you will not find inside the body of a B, as the largest vans are about 24 foot long and not much more than six wide at the narrow parts of the interior. A and C motorhomes in the 25-28 foot class will give you the living space, a permanent bed, a bathroom of usable size with it's own space (except the shower may be across the hall from the toilet/lavatory), and a tiny but usable kitchen.
But this is not going to be as maneuverable, and particularly parkable, as a B, confined to the footprint of a van. But even among vans, when you get into the city or suburbs, there are differences among vans, since a 17-18 foot van, not much longer than a SUV or minivan, is a lot easier to find a space that fits than is a 24-25 foot van (or a crew cab, long-bed dually pickup).
At 24 - 26 feet, the difference between a long B and an A like the Via/Reyo, is less than a foot of width, and the perception of the people around you that one is just a big van and the other is a big old RV.
No matter how much you move things around inside the 140 sq ft of the largest vans, you are not going to make it feel as roomy as a box almost 50% larger.