In the 50s and 60s these would have been nice working-class homes, and the trailer parks well maintained. We lived in an old park from 1957 to 1974. It was built as worker housing during WW II, and was well past its prime by the 60s. The lots were 20x40 feet, designed for trailers no more than 40 ft long. Think an international container, 40x8. Sewer hookups were basic, stick a piece of flex pipe on the trailer, and the other end into a sewer pipe sticking out of the ground. When the park was built, many trailers didn't have toilets. The park had a washhouse, with washers and driers in one room, and separate men's and women's toilet/shower rooms. Water connections were just as basic, a faucet at the bottom of a concrete pipe, about 12 inches in diameter and 3 feet or so deep. Screw a hose on. Unused connections were stuffed full of rags and covered with a board, to keep people from falling in, and the connection from freezing in the winter. Electric meters had 120V plugins, although newer trailers could be hardwired to them. Basically, today, it would be an RV park, facilities-wise.
I live in a 36x8 trailer until I was 12. Nice people, grass, trees, no trash. Not upscale, and there were more modern trailer parks in Pasco, but not a bad place to live.
When we got a bigger trailer, 64x12, it had to be parked diagonally. The park management had started doing that several years earlier, to fit larger trailers into the available space, and it made the lots a little hard to define. Nobody seemed to mind, though, and unless one had a garden to protect, people walked wherever it was most convenient.