One of the problems with trying to say what would have happened in this film is that the artists were apparently just blue-skying (McQuarrie said this) a lot of the time because there wasn't a script yet, so they were providing creative fuel to the process. So even though they illustrated saucers landing, that mightn't have even been in the script, just them showing what could me done. Likewise, the asteroid starbase/dock was just McQuarrie throwing ideas out there, as the idea of an inhabited asteroid was something he'd been noodling with for some time and on other projects.
I think it's funny that people talk about building some huge model to outdo to opening of Star Wars, because that Star Destroyer model was a tiny 3' long. I've seen it in person. They built a much larger model for Empire, but it's still only about 6-7'.