That's always going to be the challenge with replacing existing shots like the original. It was an actual shot, photographed on a stage with everything in camera(exception being the animated lasers).

That's why there needs to be more softer focus on the mtns in the background: to match existing photographed footage.

Otherwise these new shots will make more sense continuity wise but will stand out too much as synthetic.

That was one of the problems with the Star Wars Special Editions to begin with.

edit

Is there any way to more effectively tie in the fx shots with the location footage? Notice even in the original film we dont see much battlefield debris around the walkers because the stop motion animators needed the space to animate.

Maybe ady could tie those fx shots into the location footage by adding in trenches or something?