Jolly fine idea - I've also done that in the past. It gets away from the skill barrier arising from needing a commission. Also, you can indeed have characters go down the NCO route.Got to thinking about the whole LBB1 vs. LBB4-7 supercharacter skill set issue.
As noted in other threads, part of my 'fix' was the Advanced Education INT 8+ table, bringing in a lot of those later skills.
But another one is something I thought up a couple weeks ago, Enlisted Promotion.
As for adding the LBB4-7 skills, I'd say best done judiciously. If you're sticking to LBB numbers of skills then adding a few key ones is probably the best policy, and you can sprinkle them in any sensible table. Some clear candidates include:
- Survival
 - Recon
 - Intrusion
 - Carousing
 - Heavy weapons (maybe a USP for army or marine characters)
 - Ship tactics (if you use rules that make this useful, and maybe a USP for naval or pirate characters)
 - Liaison (maybe a USP for diplomat or noble characters)
 - Some sort of 'academic' cascade skill.