Layout issues with sidebar

I am recreating a design that uses a sidebar menu. However when editing the page it doesn’t show the sidebar which makes it hard to really visualize the design or get widths and such correct. Is there a way to show my sidebar while editing the page? Attached are screenshots which shows how the page looks on the frontend with sidebar versus how it appears while I’m actually editing the page without seeing the sidebar. Also when I edit my single page template…nothing is laying out correctly. Any suggestions or advice on how to resolve these issues?

It only allows me to add one image, so here is the editor layout. No overlaping text at the top but no sidebar either to allow me to see how the layout looks with the sidebar.