Thinking of... an idea: civilian units(engineers and scientists) in base defense mission. Not all 200 of them, of course, but 3-5. But how to make killing them count as decrease of amount of personell...
Well, in the same proportion. =) up to 10 civies, one standing for at least 10 people (so when having 50, it's 5 civies). If you reach a labor base of more than 100 people in addition to soldiers, one civilian counts for 1/10 of the number of civilians, evenly distributed to scientists and engineers.
Example: 100 engineers, 80 scientists, distributed to 10 civies: one civilian counts for 10 engineers and 8 scientists and you have 10 of them.
Or the starting situation as an example: 10 engineers, 10 scientists, making 2 civilians, each one counting for 5 scientists and 5 engineers.
And one additional thought on that: Scientists start at labs, engineers at workshops. If the appropriate facility is not available (transfered the engineers one day to early, the workshop isn't ready, yet), then they start at the living quarters.
But I'm not to sure about what their agenda should be. Hobbes set it this way, that the guys tend to go to the main access lift. (at least in my base layout they do.) That's making the mission more difficult as it already is. This way they are running exactly towards their demise. But what should they do instead?