I suppose if I was going to have a skill mix for a CT campaign or extended adventure I would break the 18 careers into Space, Planet, and Citizens.
Space-
Navy, Marines, Merchant, Scouts, Pirates, Belters
Planet-
Army, Sailors, Flyers, Hunters, Barbarians, Rogues
Citizens-
Others, Diplomats, Doctors, Scientists, Nobles, Bureaucrats
Decide the mix, roll 1d6 for which career per roll.
Roll 1d6/2 +2 for number terms. Roll each term’s promotions, than roll skills/improvement, than benefits.
Allow sabbatical term and charge off benefits- I allow starship loan terms for those that don’t have the credits.
Than aging.
10% immediate equipment purchase, 90% cash in for tickets, ready to go.
Note that the spacers have 4 careers with a chance for a ship, the planet careers 1 and the citizens 2. Seems about right, and especially the types they can get.
Gives the organic character feel while skewing towards the preferred campaign type and matching skills.