Hi Sol,
That's an interesting question. In terms of trying to produce a 3D view for general consumption it would need to be in a format widely available, so nothing like stereoscopic viewers, more like 3D video on compatible TVs and monitors with those silly glasses.
So in trying to answer the question you could research the Panasonic 3D video camera/lens and use one to get a feeling for the sort of camera/subject distances which produce a reasonable 3D effect for the given (very small maybe 10-20mm lens spacing on this video camera). You could then scale up that distance between the two lenses such that a reasonable 3D effect might be expected between say the moon and clouds or perhaps the much more distant starfield from 2 widely spaced telescopes.
You would have to understand, somehow recreate the image processing of this sort of thing and apply it to two telescopes .....
Best
JA
http://www.shedworx.com/files/images...hdc-sdt750.jpg
https://www.bhphotovideo.com/images/...der_723055.jpg