This is the first draft of this.

I worked several hours trying to get the character's look just right, since I'm still designing him, and in the end I decided that he looked much more anthropomorphic than the character I envision. So, I examined my existing art and LOTS of ferret photos/videos, and drew the final version you see linked from that thumbnail above.
I thought the head was what was causing the most troubles, but it turned out the biggest problem was that the arms and legs were too long. A non-anthro ferret, when standing, is almost sitting because the legs are so short. And the arms, I liked the picture I drew of him with no elbows, basically like a single-hand puppet. Puppets are silly.