I was told by the old hands in the railroad town where I grew up that cabooses were assigned to specific crews almost as soon as the first ones were made up, and that this lasted until well into the 20th century. Not only were they to get over the road, but the conductors and brakemen cooked in them, and even lived in them while laying over between runs. Sometimes, if they liked the engine crew, they were allowed to share the space as well.
Thus the connection to the cook shack seems to fit well.