Ive posted this before... similar to VG's example, but at a slight diagonal to the stick.
IE: Put the spinner northwest of the stick. This makes it close enough to reach,
but not interfering with your wrist hitting the spinner in normal stick operation.
If you need to use the stick and spinner, you will have to use player 2s stick, which isnt that bad really.
................................
. SP..........................
................................
.........JOY......X..X..X...
...................X..X..X....
.................x..............
The biggest problem however, is the trackball being so close to the left stick. With a heavy spin, you will probable smash your hand into it. You need like like a foot diameter circle of clearance for a trackball. (unless your just using it as a mouse pointer)
Edit:
If you want to get extreme, theres a few ways you could maintain the small footprint, yet get good trackball action.
1) Flip up Trackball. Flips up and out of the CP, hanging over the CP edge.
2) Pull out Trackball. On locking slides, section pulls out and hangs over the edge of the CP.
3) Pick up the CP, rotate it Horizontally, and use the Trackball located on the opposite side of the CP.
4) Pivot the CP on an vertical axis, and put the TB on the bottom of the CP.
5) Pull out locking Slide Drawer under the CP, loaded with TB's & a few buttons.
6) Front mount TB, hinged, that folds up level with the CP. (locking it securely would be the hardest part)
7) Expanding CP. TB stays in place, but both CP sides slide away from it on rails, giving room.