If its frustrating you this much skip it for now. Do two or three chapters and then see what you think you need to write into a recap that isn't covered in story. You only really need to do two or three paragraphs of the basics in recap and then the rest will come out in the course of things... or the reader will just go read OHDs. OHDs is written in full and will be the kind of thing new readers will read waiting for your next part. If they keep complaining they don't get references to the past, particularly if they think this is a direct canon thing after reading its a sequel, they are trolls or dumb enough its not worth writing down to their level. Just include that its a sequel and to what in the disclaimers.
Another method is the chunky style recap. Do the recap it little bits of each chapter. So, a paragraph or two at the begining or end of the chapter the references past actions in OHDs. Maybe its intelligence blurbs from whatever force Narutro is fighting this chapter. Maybe its a blurb from a group that notices Naruto and is now crazy paranoid. Naruto tends to get involved in things that over throw countries on a ditressingly regular basis... and he acts like the Naruto is Ero-Senin's first book.
You can also have people asking Naruto if such and such an event actually happened or not. Naruto giving short exposition on what did happen. Minus a lot of detail. This is Naruto your talking about (including the movies for examples) Naruto's first C-class mission over threw a country and involved an A-class missing nin and minion. He helped overthrow a countries revolve and made a movie with the footage. He killed a soul eating, cosmic horror so hard it caused a volcanic erupton. Add in the Sanin contections, toad summoning contract, and the Sea of Orange Doom things and Naruto's life is bordering on mythic.
Another method is the chunky style recap. Do the recap it little bits of each chapter. So, a paragraph or two at the begining or end of the chapter the references past actions in OHDs. Maybe its intelligence blurbs from whatever force Narutro is fighting this chapter. Maybe its a blurb from a group that notices Naruto and is now crazy paranoid. Naruto tends to get involved in things that over throw countries on a ditressingly regular basis... and he acts like the Naruto is Ero-Senin's first book.
You can also have people asking Naruto if such and such an event actually happened or not. Naruto giving short exposition on what did happen. Minus a lot of detail. This is Naruto your talking about (including the movies for examples) Naruto's first C-class mission over threw a country and involved an A-class missing nin and minion. He helped overthrow a countries revolve and made a movie with the footage. He killed a soul eating, cosmic horror so hard it caused a volcanic erupton. Add in the Sanin contections, toad summoning contract, and the Sea of Orange Doom things and Naruto's life is bordering on mythic.