Is this what you're after:
This setup involves using several components:
1) 1 joint hierarchy (orange joints) with a spline IK handle with an auto-created but not simplified curve. This hierarchy, along with the root joint is skinnied to the mesh.
2)  Another joint hierarchy (blue joints) to control the spline IK's curve via a smooth skin.
3)  A multiply/divide utility node to allow the length the spline IK curve to affect the scale of the spline IK joints.
What all this gives me is the ability to scale the tentacle and bend it however I like by transforming the control joints. I didn't add an option to twist the tentacle, but that won't be too difficult.