I think the wiring could be managed easily enough. Drill small holes through the top section where the start,pause, and reset section lies to keep the wiring away from the sides and possibly getting in the way of the fire buttons, because you would also need to create two other smaller PCBs for those as well plus their wiring.
And yes, if you remove the support plate from the keypad area there should be plenty of room for a main interconnect PCB there. Hell, the original wiring harness already has a ZIF like connector on it that you could probably just stick onto the edge of the new pcb and that would be more secure and longer lasting than the mylar connection used currently and allow resuse of the original wiring without modification in this way.
I don't have the software or knowledge to design such a PCB but it doesn't seem like it would be that difficult? Can even get small enough micro switches that could be surface mounted to reduce space even more. Similar to the tiny reset switch used on the turbo everdrive perhaps as an example?
In any design I would hope that all the wiring would be made with header pin connections or easy disconnects within the wiring to make maintenance and future repair on the controllers easier after the modifications.
Edited by -^CrožBow^-, Wed Mar 16, 2016 11:55 AM.