Move the red gas giant from ANH to ROTJ.
Yavin would be a different color gas giant in ANH, while in ROTJ, a red gas giant would be the planet of which the Endor moon derives from.
As such, this would be a light source from which a red tint can be added to darker scenes.
The clash of red and green would emphasize the climactic internal and external battle between the light in the dark.
The blue elements of the Emperor’s throne room would be red. I wouldn’t want it to be overbearing, still grey and mechanical, but with some red hues.
This would also be sort of a tribute to the fact that it was originally gonna be in a volcanic area.

I would want to add Fortress Vader to my version of the saga, I just don’t know at when or how. It’s just too great a setting and visual characterization for Darth Vader that I want it in the OT.