EDIT - as I said in the thread on BH, this board Zenloc is showing is PAL. So, it is slightly different from NTSC rev A boards. It is probably not an issue regarding hidden traces, but I am going to sand an NTSC rev A board just to be sure.
That cut-out you see in my Avatar is a prototype for my slimmed GC motherboard. And I just realized that it will be only slightly bigger than the daughterboard!!!