In the case of the Sharpshooters, they get paid for the second (computer op in his case) with +10 Cr for being a combatant as well. My bad, I meant to explain that. It's because a sharpshooter only gets 20 Cr. At least for now, the skills are equal, so he is roughly as qualified in both.
The same can be done for others. Transporter, for example, is not in the original. It's my title for a ground transport driver. Not a high paying skill code, probably 20 Cr. You could take the secondary code, say Scout, and add +10 Cr for the added classification.
I can go over these with everyone interested.
Also, please remember, don't take equipment from non-Alpha Dawn sources without confirming with me. In particular, there is a rather large time gap between AD and Zebulon's guide, the equipment in the latter is higher tech.