I'm assuming red is P1, blue is P2, yellow is P3 and green is P4.
Your start buttons are arranged P1-P2-P3-P4. I would move the start buttons so that it would be P3-P1-P2-P4. This way Player 3 wouldn't have to reach across the control panel to press start.
I prefer having Bart as Player 1 too. But the Simpsons has Marge as P1, Homer as P2, Bart as P3 and Lisa as P4. So don't forget to remap the buttons in that game so the characters match up to the buttons.