I was up in the loft after struggling to decide which ratskins to use when I saw these:
Now these just scream 'underhivers' to me and are much cooler models than the ratskins (which are not in the confrontation rules anyway).
So, I'll now be painting an Underhiver gang for the game instead.
P.S. Anyone who recognises the models, feel free to tell me what they are, as I really don't remember.