Perhaps the proper place to set up a display telling the bridge's story is somewhere on the Sheepscot campus, giving visitors the time and opportunity to learn the history and design of the bridge, either prior to or after riding the train.
Sometime shortly after our railroad had been rebuilt to Alna Center, I mentioned to Jason while passing over the Humason Brook trestle that after all the work that Harry and others, including the Marine Wing Support Squadron 472, Detachment B, of Selfridge Air National Guard Base in Mount Clemens, Michigan, had done, it was just momentary passing to train passengers.
We do make a point to mention the story of Humason in the museum guide booklet handed out to ticketed passengers, and the same will be done for the Moose/Trout Brook bridge. We can also ask conductors to discuss the history of the bridge with passengers.
Signs can also be posted at each end of the bridge, though I'm not sure we want to encourage hikers to the bridge unless there's an adjacent trail. Once the railhead reaches Route 218, perhaps a program can be developed to offer periodic walking tours back to the bridge. In that case, it would make sense to provide a removable panel so tour guides can show the truss structure.