In regards to the first scene, has anyone looked at the BBC show ‘The Planets’? There are plenty of establishing shots of Lava planets and red desert planets that could potentially stand in for Mustafar.

I had an idea that you could show TIEs flying over lava, perhaps past Vader’s castle, then over red desert/sea and toward trees ending with the forest battle. I’m not sure how seamless it would be to make all the shots feel like the same planet though.

Either way I’d highly recommend checking the show out, it’s beautiful!