Grant, that building behind the boxcar looks, to me, to be the rear part of a store, as it has a false front on it - an addition that was quite common on commercial buildings back in the day in the West
Going along the main drag where the stores are might reveal it if it still standing, but a slow drive up the streets behind the stores should pick it out if it's there. Another idea - is there a seniors' center in the town or in a nearby larger town. Some residents there might recognize the building in the picture, and even remember the boxcar. Who knows - one of those people might exclaim that their grandson bought the boxcar and are using it for storage on their spread! Just a thought!!