I don't believe there has EVER been a real arcade game with a 4-foot wide control panel. Even dedicated 4-player units usually came in at under 3 feet.
You can do 2 player + 4-way + trackball on a 30"x6" panel with room to spare. (Hint, place the 4-way joystick right next to the player one 8-way, it is the most comfortable place for it, and allows it to use the same buttons as the 8-way, it might not be symmetrical, but it plays wonderfully, if you want to be symmetry then give the 2nd player a 4-way as well).
The trackball alone should give a decent enough spacing between the players. Extra room to the left of player one or to the right of player 2 is always entirely wasted. Anything there can be chopped right off. Most 2-player cabinet literally had less than 4 inches between the 2 sets of player controls. A trackball alone takes up more space than that. So if you have a trackball between player one and two, then you already have more elbow room than 90 percent of games ever made, anything else is bonus.
Putting each stick towards the middle with the first player having the buttons on his left is bad design. No game EVER came that way (in fact very few games even had right hand sticks, and no newer games had them). It isn't just bad design because it is incorrect (and incompatible with the muscle memory people might have from real games), but also because it creates the need for more elbow room. Your joystick arm moves around quite a bit, while your button arm tends to pretty much stay in one spot. Putting the 2 wildly moving arms next to each other is bad.
I would personly redo that panel before you spend any more time on it.