I found a 2mb version of the first which is smaller because it's lower res textures and no bodygroups or whatever, however it's an NPC not a playermodel specifically, not sure if that would work?
Also excuse me if I sound condescending, but...how on earth is the second model "too close to a brood alien"? Just because the face isn't visible? It doesn't make much sense to me, that looks absolutely nothing like a brood for reasons which should be too obvious to state, and there's already models in the pointshop without visible face, not to mention you can give your model mask/hat additions that completely conceal the head anyway? It just sounds kinda silly to me.