When Zach Peterson started Exact Plumbing in 2006 with a pickup truck and a 12-foot Haulmark cargo trailer, another plumber predicted he’d switch to a truck or a cargo van within a year.Good thing that plumber doesn’t moonlight as a fortune-teller, because a decade later, Peterson and his Haulmark are still going strong. In fact, Peterson has modified the trailer to the point that it’s now his most valuable business partner — an eco-friendly power plant, rolling billboard, cargo carrier and productivity enhancer all rolled into one.“Using a trailer is the best thing in the world for plumbers,” says Peterson,
