That sounds like a very unnecessary dividing of the usually limited soldiers available.
Actually, a security team wouldn't divide up the limited resources of personnel, since if a base had an aircraft present, such a force wouldn't be needed (they could just deploy out of the dropship and defend the base, in a manner of speaking). I was thinking of the same idea, with the security team, but I was going to call it "base garrison". The only real problem is that this "aircraft" would need a hanger.
I feel the quickest way to code this would be to call it an aircraft with no allowed equipment, and no fuel capacity. Thus, it would only be eligible for base defense. To save space, the "aircraft" should only require a small hanger, or maybe even a specialized hanger that's really cheap, and only eligible to store this "aircraft". Also, the production costs and time should be very low, such as 1 hr for one worker and a couple hundred dollars (enough for barbed wire, I guess). And, don't forget an awesome UFOapedia listing!
After all, that's my favorite part of playing the game!