The following is not the sexiest of careers, and it's not particularly a gap in the core book (it's covered by citizen and rolling Drive), but does at least generate a playable Traveler. And its not hard or time consuming, the longest part was the Events table and I'm still under 30 minutes.
Taxi Driver
Survival Dex 5+
Advancement Int 7+
Personal Development
1 - Dex +1
2 - Int +1
3 - Carouse
4 - Streetwise
5 - Gambler
6 - Gun Combat - Any Pistol
Taxi Driver
1 - Drive (any)
2 - Navigate
3 - Electronics (Comms)
4 - Persuade
5 - Streetwise
6 - Drive (any) or Flyer (any)
Mishap - as Citizen
Events
2 - Disaster: as Mishap, but you are not ejected from this career
3 - Driving criminals gives you an in on another world. Gain one of Deception 1, Stealth 1 or Streetwise 1.
4 - Driving gamblers and high rollers gives you some tips and new introductions. Gain Gambler 1 or Broker 1.
5 - You thought you were keeping your eyes open from the beginning, but practice makes perfect. Gain Recon 1.
6 - Working on your own vehicle gives you Mechanic 1, or any Electronics 1 if you already have Mechanic.
7 - Life Event
8 - You're turning into a lifer. Increase your highest Drive or Flyer skill by 1.
9 - You buy a gun and practice with it, gaining Gun Combat 1.
10 - Between passengers and learning tapes, gain a new Language skill at 1.
11 - You go owner-operator. Keep a Vehicle when you muster out, and gain a +1 to one cash benefits roll.
12 - Charming the passengers pays off. One is inexplicably impressed by you, and you gain a +4 to qualification roll to enter a Citizen or Rogue career next term.
Cash Benefits table as Citizen
Other Benefits
1 - Gun
2 - Vehicle
3 - Int +1
4 - Dex +1
5 - 1d3 Contacts
6 - Implant
7 - TAS Membership