There has never been a traditional sign for Arkansas as well as some other States and your "invention" would not be universally accepted EVEN IF ASL is a living, evolving language; it just won't catch on. Since the abbreviation, "Ark" is quick and short when you fingerspell it, consider it as a "sign" for Arkansas.....
Interesting discussion, Tousi! I can see how this can become a matter of linguistics and I like you brought up that point.
I'm not sure I agree completely, though. ASL is a dynamic and evolving language, but what makes it evolve are the contributions of individuals. Here's a good example. I know of a sign for "nerd" that involves the "4" handshape placed on the chest (where you would have a pocket on your shirt) to demonstrate the pens famous with the nerd archetype.
That sign came from a woman I know who decided to put it into use one day. It's now in general use in my social circles, and when I went to Gallaudet I was using it liberally.
The point here is that, yes, manufactured signs aren't always easily added to the language, but without manufactured signs, you'd have no ASL evolution. I think the test here is if it "feels right" -- a strange concept, but maybe one that makes sense in a Noam Chomsky way. The original sign I encountered for e-mail (e, then mail) was awkward and fell out of use pretty quickly for another manufactured sign that feels much better ("c" handshape non-dominant, with bent "b" handshape passing through from anterior to posterior).
But Endymion is not a PhD in Linguistics. Right, Endymion? Yep, Endymion.