An experiment.

[Xeram]

Or here's a real wierdo suggestion - what if every 10th pick (starting from a random 0-9th pick so the heads arent always excluded) was both their civilian and security role? i.e. Security Chef, Security Janitor, Security Assistant, etc - Start with the standard civilian uniform, corresponding ID + Sec access, and a backpack with all the sec gear they'd normally need in their off hand. 

That way you can "fill" sec, but also not get roundstart suicides from people who really REALLY wanted to make borgers. They can just make borgers from brigmates.

Can we all pause and look at this for a second, not once ever in all of my thinking about this had I ever even considered something close to this and reading it made my expression light up in a way I haven't for a long time.

This is pretty much the logical conclusion of "Everyone hates security, vigilantes don't get nearly as much hate and get the job done". Turning the soulcrushing job of securing and defending the station into a much more localized, secondary goal of (hopefully) appropriately spaced crewmates. Basically going from hired mall cops to station millitia.