WOW!!! you are putting allot of effort into getting it fixed. Don't know how much you are asking for your services but I assume it would be lower than the original costs of a new wiikey. That being said he's getting it for a steal for the amount of work you are doing.
Just a quick note. You said that pin 28,27,26 don't need to be wired for a sd loading wiikey?
So just to be clear which pins need to be soldered to the gamecube for sd loading only?
I always just solder all the pins except pin 30,31 and all different ground wires just into one thicker ground. Would make life a little easier if I needed to solder less pins
EDIT: I see you have removed the left 2 chips. Those are needed otherwise the wiikey won't work properly. Unless you have found a way to remove them
and still have it working. I'm all ears/eyes