SM measurements and tails

[Roh]

I'm stating out a sapient species I made GURPS Space. It turned out to be small but luckily at least the top end of small. All of 10 inches long. But then it ended up being winged. And reading flight winged I get the impression that your wing span is not what you use for SM length. But then.. He also ended up with no limbs beyond a tail. So, do I count his tail in that 10 inches cutting his actual size in half effectively? It's a constricting, prehensile tail actually so I am imagining it should probably be near the length of its actually body so yeah. If I include the tail that makes the body where all the organs are 5 inches long.