My thoughts:
I agree that the left joystick looks too close to the edge of the panel. It certainly looks like you'll have a problem.
I don't like the fact that you have no panel space under the left joy. I like some panel space to rest my arm, but you said you don't. Will the other people playing your cab want some space? If so, since you said have to keep the curve, perhaps you can move the joys forward some on the panel or make the panel a little deeper?
I don't like two sets of TB buttons, and don't like the placement of either set you have there. Do you need the TB buttons to act as mouse buttons? If so maybe you can place them above and to the right? If you don't need them to act a mouse buttons can't you just use player 1's buttons when using the TB?
What are the 3 buttons above the spinner? Are they for game play? If they are, wouldn't they be awkward to use while using the spinner?