I’m now using @nontroppo’s 3rd option to compile to .MD which is opened in Nisus Writer Pro, where a macro turns it into styled RTF (NWP’s native format). The thread below gives the details of where I’m at with it at the moment and includes a Scriv project to play around with; if you don’t use NWP that’s not important as the .MD file is saved anyway, which you can open in whatever app you use for that purpose. All you need to do is: use the Basic Multimarkdown compile format; assign all section types to a single text layout which has a heading; under the gear menu, switch on “Convert Rich Text to Multimarkdown” (I turn off “Escape special characters” so as not to interfere with my Bookends temporary citations … but again that need not concern you necessarily).
Mark