Ok, figured out why a section isn't valid here. Sections are used in a layout to render part of the page. Each page that consumes the layout can then insert content. For these pages, they don't use the standard default layout as they don't need any of the components of the page (i.e. navbar, sidebar, header logo, etc...). In effect, these pages (closed & preview) are more like the layout than a page that consumes.

I do however want to share the header and the footer so that I don't copy/paste the whole lot, so a partial is the way to go.