I have similar hands and I just claw everything.
I actually claw with my wrist on the pad so that I can rest the part of the hand shown in your picture.
Deathadders are unusable for me because of the hump location, the only mouse I can palm is the Intellimouse 3.0, you should try the new one.
Anyway I find it faster to click with the harder point of the finger rather than the softer digit pads.
"a bad joint can't be that bad right?" -q