The non-compromise answer to that is the Cutter. I run a fully engineered trade Cutter, 736t cargo, 2400MJ highly resistant shields, dual A5 SCBs, a little over 300 DPS, getting away at mear 400m/s, impossible to masslock except by another Cutter.
That's one ship and one that is locked behind a rank and one of the most expensive ships in the game.
Having only the most expensive ship from a superpower as a viable method to bulk trade in this game is a good example how broken the whole PvP aspect in this game is.
I understand that balancing an open PvP game is extremely difficult, but in the last years FD made things worse and worse by adding module after module in a desperate attempt to balance the game and by doing so they balanced it for "big ship wing PvP".
The module inflation made the gap between trading ships and pure combat ships bigger and bigger.
Special effects add additional requirements that reduce the options for traders.
Bulk trading is about credits per ton and hour. Below a certain threshold it simply doesn't make sense as other methods of earning credits are much better. Bulk trading already is more of a hobby than the backbone of the "economy".
Add the concept of a "pirates share" and trading simply doesn't make sense in Open Mode.
In the end this discussion doesn't matter. Only FD can solve this problem.