If Robbin McMain gets another rent increase, she’s worried she’ll become homeless. McMain lives in a 55-and-older mobile home park in Brookings, Oregon, where she—like many other such residents—owns her mobile home while renting the lot it sits on. This year, McMain and her neighbors all received a 14.6 percent rental increase—the maximum allowed under current state law. For seniors who are on fixed incomes, the increase is squeezing their limited budgets and upending their...