Ziz said:
Actually, I think that matte was painted for the deleted Sandstorm scene.

And the bit about Luke building his saber with spare parts in Ben's attic explains why his ROTJ saber looks so much like Ben's ANH saber.

I may be wrong but I can't see how that matte would work in that context.

The skiff takes them to their ships (in a sandstorm) and they get in them and leave so why the daylight and the hole for live action filming to be plopped in?

It fits in with the cave story much better but who cares as either option is beyond restoration without very good look and sound alike actors or time travel, and I'm just a nerd and not very knowledgable about such things, well not on this planet, in fact I'm not very sure which planet I'm on...