Playing around with it the "nav" function does not allow via modifiers as far as I can tell, the "run" command. It tries to run when using trade.py run --capacity 100 --credits 100000 --ly-per 18.8 --from Bast --via Aedaenon --to Damna but throws errors of not finding pricing data (well I didnt import it so that makes sense, but I do not really want that function) cannot find Aegaenon and a few other errors.
Python might be the way to go, but as far as I know the is no complete database of all inter-distances between stations other than my spreadsheet & the one of the forums (forget the persons name)
Ty for pointing me on to this though!