Regarding fitting the track ball in, I have to believe there would be a way with the space you have. Move the joysticks outboard to the limit you mentioned, and if that is still not enough, pick up the rest from moving the buttons closer to the sticks and/or moving the buttons closer to each other.
The spinner placement should work, but be aware that if you have any meat head buddies that like Golden Tee, they'll probably smash their fingers into the spinner by trying to crank on the track ball like a hero (even if you explain to them in single-syllable words that putting one's entire body behind a shot in GT is not needed to get maximum distance).
What games are you planning to play that require two 4-way sticks? There aren't very many.
Like left and right mittens for your hands, I think the designations "player 1" and "player 2" are kind of self-explanatory and don't need labels; it's up to you of course, but IMO those labels are just clutter on your design. Same with the rotational arrows... personally, I'd move those to an instruction card on the bezel or leave them out.