Yeah, true, although if we’re removing the Second Death Star from the film, we’re already deviating from canon, since it later appears in TROS.
I think I would only use non-Star Wars footage if this version of Return of the Jedi was meant to be the last Star Wars film. Hell, I have a bit of free time. I don’t think model making isn’t out of the question for me. Maybe using similar techniques that they used to make the bladerunner city footage.