I dunno... it seems like it would still be a problem. The old way to do spacehips in film, ala star wars, was to do the bluescreen background shoot, then use acid to remove the blue parts of the film. The acid was a very inexact process. Too much and you would eat away all your scene, too little and you wouldn't get a good clear area.
Now the edges of the viper cockpit would be fairly easy to do in space, since you can grow the matte to be larger. The extra black matte would be invisible against the black space background as you indictated.
But to do a bubble cockpit requires the edge of the cockpit glass to show up on film, which is hard since it is glass. And also you have to be able to make a good matte of it.Which requires exact acid corrossion across a large footage length of film. I don't think it was possible back then. Your cockpit glass would tend to appear nonexistant in space. Which looks funny. And in atmosphere you would get that corroded matte that you often see in bad chromakeying.
