Maybe it's an idea to "supply" your characters (or faction) with for example fuel, food rations, engine components, etc. (It is already in use on an other FL server and i think it works well. The only thing is that they have it only for the servers factions)
You transport the goods to your "home base or planet" and the total ammount is recorded, every day/week/month you run your characters you have to pay a certain ammount of those goods. When characters for example go in deep red for more than a month or so(negative balance) delete them.
This way people have to use their traders not only for making money, also for running their characters. And how bigger the ship is the more supply they need.
It is also a RP thing. Transport factions can be hired to get those supply's, pirate factions can attack those to get the supply's on their RP way. Escorts will be needed more, so are police and military factions to make systems safe.
Make it a level 30+ thing, so the new people on the server will only have to concentrate on making money untill they reach the 30+ level
I dont know if it is possible to hook this to accounts, but recording your money and kills per character is already done.
