You brought back some of my best memories with this screenshot.
I agree that it can be done with contrails ,fairly easly I would say.
Just set contrails at the same location as thruster glows ,then enable them it FRED (just like for nebula missions).
You can easly manipulate the lenght of trail ,just change "spew time" in table.
http://www.hard-light.net/wiki/index.php/Ships.tbl#.24Trail:
This wiki entry should also help you.
In fact ,I have already done such thing ,though it was related to contrails forming in atmosphere.
I'm attaching some screenshot's of how does it looks.
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