A class B so used will have room to sleep, limited wardrobe, tiny kitchen, and minimal toilet facilities needing frequent maintenance. If you are into bathing and showering, you will be looking for external facilities, or RV hookups to support your limited built-ins. Cooking will depend on a limited supply of LPG, and without an external electrical hookup you will have no environmental cooling, and maybe no refrigeration (limited more by electrical power storage than LPG capacity).
Having been married 43 years to working woman(and raising two daughters), I can't imagine her getting ready for work with no running water and no electricity.
With no job, no need for the income, yes I could imagine living for a while. Hippy era, we did it, nobody worked, no showers for months at a time, never washed clothing; peace, love, and a reality defined by LSD.
But in this era, what you are proposing fits into "homeless living in a car." Depending on where you are coming from, that might be a small step up or a big step down.