Skalp layers are managed automatically and should in effect never be touched. Unfortunately we are unable to hide these layers from the Sketchup Layers panel, so the next best thing we can do is trick SketchUp into moving all our specific Skalp layers right to the bottom of the layer list, regardless of sorting order.
We’ve also added one extra empty layer serving as a marker / friendly reminder indicating all ‘Skalp’ layers below this point are to be safely ignored and left alone. Mistakenly fiddling with Skalp layers is often a source of unwanted trouble. We think moving these layers down and more ‘out of sight’ makes it a bit easier to avoid hitting this trap.