It probably can be done but you’d need a supportive landlord and some luck in not attracting negative attention from neighbors and city officials. It’s not a legal dwelling so if someone complained you’d be done. Maybe not a big deal in a camper as then you could move quickly, but to where? I’ve seen vans around Cambridge and Somerville where I live but they disappeared in the fall. Nobody seemed to bother them in the summer. In the cities of course they’d have to move often for street cleaning, although some were on private driveways. Luck with neighbors largely depends where you set up. If you found someone with a backyard in my neighborhood in East Somerville and built a yurt or parked a RV, absolutely nobody would care. But in more expensive and lower density areas like Arlington you might have a problem. Getting utilities is also a problem. The only MA towns that allow “tiny homes” are Great Barrington and Nantucket so not Boston area, but since 2019 Somerville allows an ADU which is basically a tiny home in the backyard of another house (city officials couldn’t cite any examples when I called recently). There are subreddits for tiny home, van and RV dwellers that would be helpful.