I wrote up an unstreamlined 400 T merchant with deckplans (in J1, J2, and J3 versions; same hull, different interiors) for JTAS Online once. Being unstreamlined, it only serviced routes where the starports had orbital components. With a high correlation between enough traffic to rate an orbital starport and enough revenue to fund decent system defenses, it was usually unarmed, but it did have the hardpoints for installing turrets. Also, the huttle had fuel scoops and a collapsible fuel tank in case of misjumps. When it became old enough to dispose of, the new owners could install turrets and take it into the backwaters. It did take 11 or more shuttle trips to load/unload a full cargo, but as free traders tend to spend five days in each port, that wasn't so much of a problem as it would be for a regular freighter.
Here's the link: http://jtas.sjgames.com/login/article.cgi?792
Hans
Here's the link: http://jtas.sjgames.com/login/article.cgi?792
Hans