Having set a pattern of following up localized opportunities opened up by railroad construction activity, Eccles then acquired some fir and white pine timber tracts in eastern Oregon, at the time the Oregon Short Line was being completed from Pocatello, Idaho, to Portland, Oregon. He built a planing mill, shingle mill, and box factory, then a larger lumber mill, an electric plant, and other enterprises. Soon he set up other mills at other locations in Oregon and Washington. He invited friends and acquaintances in northern Utah to go to Oregon and homestead timber tracts and work for him. He and his associates also built the Sumpter Valley and Mount Hood railroads. All of these operations were profitable and Eccles shipped much of the finished lumber to Utah where it was used in building homes.

Shortly prior to his debut in Baker, Eccles was admired by Ellen Stoddard, the daughter of one of his partners, John Stoddard. As loyal Mormons, both David and Ellen recognized that he might marry a second wife. After a brief courtship they were married. Ellen remained in Baker for several years, after which she established a home in Logan. She and David had nine children.