I heard the occasional complaint during my time at Pontoon Beach — kids riding their bikes in the street, potholes patched instead of streets repaved — but they sounded like what you might hear at the monthly meeting of a suburban homeowner’s association. More typical was the view of Alisha Stanek, a 22-year-old high-school dropout with an 8-month-old daughter. Including the installment payments on a used, three-bedroom, two-bath trailer, she was spending $550 a month on rent. “I couldn’t find a house for even close to that,” Stanek said.

Others even expressed feelings of superiority to those burdened with big mortgages or hefty monthly rents, including Barbara Watz. She moved to Pontoon Beach in 1978, a single woman in her 40s working at a blood clinic. She could have bought a tiny house on her salary, but a two-bedroom, one-bath trailer cost less per month than her car payment — and meant she was done with house payments after a few years. Now 76 and retired, Watz pays $285 a month in lot rent and spends her days reading murder mysteries and tending to her plants. Watz drives a 2010 Honda S.U.V. and has the money for small splurges. (One day when we were talking, U.P.S. delivered to her a box of wooden ducks dressed in yellow raincoats.) Her only complaint about living in a mobile-home park? “The trailer trash, redneck jokes I’ve been hearing since the day I moved in,” she said.

There’s some nobility in the Rolfe-Reynolds business model. The parks they take over tend to be in lousy shape, and they spend hundreds of thousands of dollars fixing them up. In that way, they’re the trailer-park equivalent of the developer who buys abandoned properties in the Bronx and converts them into livable places that are, at least, clean and safe. “There’s more money in decent than slumlording,” Rolfe told the class in Orange County. Run a lousy park, he warned, and you’ll never keep tenants. They’ll skip out owing rent, and it will cost you thousands of dollars to fix up the trailers they trash before leaving. Rolfe says he shudders at the thought of losing money to the multimillion-dollar negligence suits that result from cutting corners.

A Rolfe-Reynolds park is, if nothing else, well run. Based on what I saw, tenants kept their lots junk-free and the grass mowed — or management will take care of things and send you the bill. Rolfe and Reynolds begin eviction proceedings on a tenant as soon as local laws allow, even if a tenant is just two or three weeks late in paying the rent. “Ours is a strict ‘no pay, no stay’ policy,” Rolfe says. The practice helps rid their parks of bad seeds and ne’er-do-wells — though that’s little consolation to the newly laid-off tenant who now has to simultaneously think about finding a new job and a new place to live, while facing the possibility that he’s about to lose whatever equity he has in his home. And most do have considerable equity invested, given that four out of five are paying only a monthly lot rent, which means they own their trailer outright or are making payments to a third party. If their trailer parks can be viewed as part of the new safety net, it’s a fragile one.

The trailer park also seems a bad deal for the manager. After all, it’s the managers who deal with a clogged sewer line or the unstable tenant behind in his rent — in exchange for a low-paying job that doesn’t even offer health insurance. Yet Rolfe has a point when he argues that it’s often better than most of the alternatives. He mentions Linda Wright, who manages his park in Arnold, Mo. “What was she making at Walmart: $13 an hour?” Rolfe asked. “For $25,000 a year, she had to be in that store eight hours a day, driving there, had a boss. Now she’s making close to the same with us, in her own house. She’s her own boss.”

Rolfe confesses to feeling some guilt that he owns the largest house in his hometown while his customers are making do in cramped quarters. It breaks his heart, he confesses, when they evict a family even as he tells himself it’s for the best. He acknowledges he has made millions of dollars warehousing those living on the economic margins. But what if you simply want to keep your monthly living expenses low so you have a nest egg for emergencies — or have the option to take in a movie or buy some wooden ducks every once in a while? Or what if Pontoon Beach is simply your best option? With around 10,000 lots scattered mostly across the Midwest and the Central Plains, Rolfe and Reynolds are about equivalent in size to a public-housing agency in a midsize city — and in an important way, they play the same role. Those living in public housing are generally required to pay up to 30 percent of their household income as their share of the rent. Rolfe and Reynolds’s tenants pay on average closer to 20 percent. And unlike the civil servants working for a housing agency, their managers know they must enforce the rules or they’re out. “We go through managers like crazy,” Rolfe says.

Their tenants, though, tend to stay if for no other reason than a lack of options. The average resident has “such bad credit,” Rolfe said, that it would be a deal-killer for most landlords running credit checks on potential tenants. Those who are retired are thankful that they own a place of their own, even if it’s only a metal box, because it allows them to live on the little they have. And here Rolfe and Reynolds are providing safe, low-cost housing to those who can’t afford to pay more or choose not to.

“We’re the Dollar General store of housing,” Rolfe said, adding, with an amiable grin, “If you can’t afford anything else, then you’ll live with us.”