Wouldn't helper pushers, be shoving against the "Crummy" ... making it easier for the helper locomotive to be cut off at the top of the grade ?
In Enola yard they shoved several crummy's up a short inclined caboose track, and when an outbound train needed a caboose, they released the handbrake on one caboose, letting just one roll by gravity down the grade, where it was coupled onto the westward outbound stopped train.