I would not drill a single hole or print any artwork until you set up a 48" wide panel at the exact height and angle you will have it on your cab, then stand there at each control and see how it "feels" even if you are just using a printout to show where the buttons and joystick are. I made a lot of little adjustments once doing this, all would have been critical adjustments. Also, be sure the P3 and P4 joysticks are parallel to the screen, even though the buttons are angled.. Think of it like a mouse, even if you are at an angle to the screen, you will still use the mouse relative to the screen, not to where you are standing in relation to the screen.
If you have the patience and the time, I would make a complete cardboard mockup of the control panel, wire it up to your controller, set it at the right height and angle, and try to play a game. As extreme as that might sound, it is the best way to ensure you have things the way you want them. You might end up shifting some controls around, moving admin buttons, etc. This is particularly important with alternate controls like trackballs and spinners.