Speaking of more Mustafar establishing shots, I don’t think I’ve seen anyone suggest using stock footage. Adobe Stock has some pretty cool footage of both forests and lava rivers side-by-side. The lava would help the audience mentally connect the planet with Mustafar, as well as establish the burning forest Kylo is in. Here are some good examples of that kind of footage. With proper recoloring it could be made to match the Mustafar scene well.
The big con is that it will cost money to use any of that footage. But I would be willing to help pay for it if Hal or others discovered the perfect shot to use. On the plus side, we won’t have to worry about stealing someone else’s footage off of YouTube, because we paid for it. Also, we can use high quality, 4K footage, rather than a YouTube rip. Might be something to think about.