This is a bit of an aside, but a very realistic application of Orbiter is to kill my time and productivity.
Now, to your question about independent vessels:
Sure, though they will not have the precession of Orbiter's MFDs. IRS and other technologies can do amazing things, but tiny amounts of error add up quickly on such a large scale. We might get there someday, but as jedidia said, for our solar system it doesn't make much sense.