cutting a long object into several parts is a bad idea. 1 object (fence) will turn into 5-6, and there can be 100 or more fences and there are still other objects.
Can you snap them to the grid? That way, the fences in your video would take up 2 grid cells, and you'd only need to cut them into 2 pieces.
I saw a similar project recently where they ended up cutting the objects using meshes and then combining them into a hierarchy.