So I think I remembered more this time.
First, I discovered that loop cutting wasn’t finding the ramp properly. So I cleaned up the geometry by removing the stray faces and edges from before.
Then I could make loop cuts. I made three total, two for the railings and one to give the pyramid summit some vertexes to snap the railing to.
Extruding the railing was easy, but to keep the bottom part at an even height I directly adjusted the transform of that edge.
Then in anticipation of what I might need to do, I cleaned up the geometry by removing faces and removing doubles.
