Cutting Planes
Open a level.
Add Simplygon clipping plane visualizer.
Select Simplygon clipping plane visualizer. Add planes. Update parameters and click update.
Open World Settings tab Window / Standin Outliner.
Select static mesh actors in level editor.
Click Create in Standin Window.
In the settings panel for pipeline choose Far.
Modify Far pipeline settings.
Modify clipping geometry settings. Check Use Clipping Planes
Build Standin.
Finished Standing with clipped top and bottom.