I may be over-simplifying this somewhat, but thought I would post my solution for ladders here just in case anyone finds it useful. It is extremely simple and quick to set up, and produces exactly the behavior that I wanted. (Though others may want more for their games)
First I created a simple ladder blueprint and in the components tab made the ladder out of meshes in the example content:
Note: make sure that the ladder volume (box component) extends far enough above the ladder mesh to allow the player to step off once reaching the top.
Next create this graph in the ladder blueprint graph tab. It simply sets the players movement mode to flying when entering the volume, and walking when exiting it. (Walking works better than falling as it ensures that the transition at the top looks natural)
Final step in next post since it only allows 2 attachments per response.