Because I have the Winterized Medic Armor, and the Samurai armor, but I feel as though I'm missing something. Confirmation would be appreciated.
There are a few other outfits to be found in Mothership Zeta:
General Chase's Overcoat can be found in the Waste Disposal Area, and Paulson's Outfit can be had if you're willing to kill Paulson, or do some Reverse Pickpocketing to get him to equip something else.
There's also the Spacesuit, but I'm assuming you've just not mentioned that, as it's something of an unmissable quest item, and also rather useless.