There's a 3D hand model roaming around somewhere that you can put into the Dactyl model and give it a try. Also, if you know anyone with a Kinesis Advantage (2 or 360) you can test drive a default Dactyl (it's based on that). I 3D printed mine blindly knowing that I have smaller than average hands and want more aggressive stagger + tent and it worked out really well for me.
Also check out Ergogen and Ergopad for truly customized to your hand experiences. This video is a great primer.
How did you get it for cheap?