That shouldn’t require more complex configurations than a custom toolbar.
I agree, and I’ve considered that myself. One thing I’ve juggled around in my head is an idea for a package that maintains your table of contents for you. That is, it looks at the directories containing your text, puts everything in the order you tell it to be in, provides a pane or modal containing a mockup with links to jump to each section, and will export into Pandoc or markdown when you’re ready to assemble the document. There are a couple of packages that generate a TOC from a single markdown file, but they are simplistic and don’t do much for someone while they’re editing. What I’m imagining would be like a living outline that’s constantly updated (with optional annotations) so that you can stand back and see the whole scope of your work.