Last Guy in the Airlock
Mechanically? Off the top of my head, give them 2 backgrounds. So you don't just have a Noble, you have a Noble Scholar. You don't just have a Criminal you have a Criminal Sailor (ie a Pirate).
I have no idea if that would work but I can think of a bunch of combos that don't seem overpowered but offer a lot of color.
This is my solution for fixing rogues....