Is there a way to temporarily remove a bunch of items in CK, similar to how if they are all linked to a parent and the parent is disabled in-game? This would save me moving a lot of stuff, to see the other things underneath/inside

Select the object and press number 1 twice. This will hide the object in the render window. Press F5 to refresh and they will appear again.

You can also just hit Alt+1 and they will all reappear instantly without the re-render wait. (Though it can be buggy so F5 may be better at times)