My IA and I are helping a buddy of mine on his airplane. He's got a wing walk rib with a small crack. My IA wants to install a doubler. The problem is, it is going to be very hard to reach a few of those rivets with a bucking bar via the existing inspection hole. I'm looking through the AC43 book right now, but I also wanted to see if the PF hive has any advice.......can we install an inspection plate in the bottom of the wing, in any open area of the wing skin that doesn't interfere with any other structure? I see you can do a patch most anyplace, but I haven't found anywhere in the AC43 that outlines installation of extra inspection plates.......