I need to create a page or post hierarchy

I am currently stuck and I need some advice ASAP. I am making a site for a client on which they need to have a sort of hierarchy like this

Carriers (Main Category or page)
-Level 1
-Level 2
-Level 3 (sometimes needed)
-Level 2
-Level 2
-Level 1
-Level 2
-Level 2
-Level 1
-Level 2
-Level 1

I was thinking about doing it through parent and child apges but that would create a ton on empty pages which purpose would only be to hold the children.

I also though about doing it through post categories but I am not sure how to do that since the hierarchy isnt always consistent, some have 3 levels and others only one. Can you please help?

Thanks!