For distant star base, I have found what seems to be an exploit to me, if you can build a ships with multiple constructor modules (the more the better).
If you use them all save the last one (so ship still exists), then upgrade ship to a different model, it will have ALL the constructors of that model.
So if you have 2 models wiith multiple contructor modules, then you can send A ship to remote location, and upgrade all you want, for a bit od down time to 'upgrade the ship' which is often far less time then you could send new ships from a distant shipyard.