I had a concept for a twinked free trader that was more of a stock hull fitted out with some goodies. Co-incidentally, MTU also has a 'stretched' A300 class trader, although note that my stuff was CT so not so relevant here.
Essentially, the A300 trader was a J2 ship, and IMTU I had 2G and 3G variants of both the A200 and A300. The 'twinked' version had an uprated electronics suite, essentially a model/4 computer.
This computer was an avionics package sold as an 'export' model, mainly aimed at light warships such as system defence boats, heavy fighters or patrol craft. It was a (relatively) low maintenance package sold to satellite nations or client states that was somewhat effective in combat but relatively cheap and easy to maintain. Obviously it was less effective than a state-of-the-art system.
Even with a relatively modest weapons fit-out, pimping the electronics does surprisingly good things for the capabilities of your ship in combat. It will give you bonuses to hit, bonuses to defend, better sensors, ECM and so forth - the specifics depend on which rule set you're using.
You could possibly also go for a milspec hull, which adds some armour, much as your ship has, but I decided against that.
This concept gets away from the notion of a specific 'frontier' trader and goes more for the idea of what one might do with a standard design.
Of course, if some rifraff like pirates were to get hold of one of these avionics packages the party might be in for a nasty surprise ...