DD, I thought some paddle games required the paddle to be in port 2 to work? That is the only reason I thought you might need two cords, but you clearly know a lot more about this than I! (I really only play Crazy Brix but DAMN do I love Crazy Brix)
Frankly I think 4/8 way is enough, and easy access can be had with a case with hinges. Though I have no pics any longer, I built a 7800 controller into an old Glock handgun box, which turns out to be great for controllers, and is easy to open. Although....plastic snaps...they won't last forever.
I CAN'T steal any of your thunder as your work is leagues above mine but I built this years ago and always want to add a paddle controller to it. I'd just have to lose the sticker.
BTW all your controllers are amazing but that black and orange paddle model....*chef kiss*. Amazing.