Most municipalities hate mobile homes and have strong prohibitions against them outside of specifically zoned areas. In the case of this Spartan although it is larger than a normal travel trailer it is still smaller than most mobile homes, which are generally built of modules 54-60 feet long and 12-14 feet wide. This one is only 10' x 50', closer in size to a large "toy hauler" travel trailer meant to hold motorcycles or ATVs plus living space; some of those get up to 40' long and 8'-6" wide. TOL motorhomes can be even longer, up to 45', and both those and large trailers often have "slide-outs" that increase the width significantly.
Given that the aesthetic of the Spartan exterior is very much that of a '50s or '60s streamline travel trailer and not a conventional mobile home it would be interesting to try and park it in a backyard on a driveway. It also still has a hitch and wheels, both of which are usually removed from mobile homes once they're permanently parked; it's not unusual for mobile home axles to be removed and reused as well. Using the Spartan as living space would unquestionably be illegal as parked vehicles are considered to be stored and not additional living space, but you might be able to get away with it in some places provided it was fairly hidden from the street. It would certainly make a fabulous guest house, I know I'd want to visit.