A teacher in my school does something like you are suggesting with the 'Description' question type. All questions are on separate pages, shuffle is off, and free navigation is off. The student has to take the quiz one question at a time in a specific sequence. When thwy get to the essay, they submit their open ended work and click next. When they go to the next page, they see the description block with a PDF resource in it (or you can put the feedback there). I don't know think the student could then go 'back' and rework their essay response, but at least they'd see the feedback right away... Sharing in case this could work in your situation.