Stealth "kroot"

I'm So I found these minis from reaper minis. When I first saw them I knew I needed them for my tau army. The plan is to model them with light armor, and re-breathers (they are fish). Some one told me the look like the could be a kroot sub species which would work for the fluff. 

I bought a tube of green stuff and did a couple test helmets. I plan on getting some grey stuff to stiffen up the putty, the green stuff is not create crisp edges as I'd hoped. I also want to get instant mold so that I can recreate the armor with press molds. Here's the final mock up of the helmet that I'll probably stick with. 

Once they are done I'll use them as stealth suit "count-as". I would like to beef up their stats and points because they are larger then standard stealth suits.