I absolutely envy you. I have been working on my Hobbit Edit for over two years now and constantly bang my head against shitty shots that are still somehow essential to the overall story. You simply have access to resources I can only dream of, like replacing a son with a piece of wood 😉
Honestly, I should start stealing shots and ideas from you…
It can be very frustrating work my man - I know what you mean. I spent just a little over 2 years on mine. All the footage I use is sourced from both theatrical & extended editions of the films. If you want to borrow footage that’s fine, but just remember to give credit and I also have a subtle 35mm film grain/my own color correction (for best quality to edit, download the Blu-ray ISO version).
Or, you might like this, check this video regarding the VFX and read the description https://www.youtube.com/watch?v=Gm2CDRDPJmU for you may find some useful things 😃