The issue is that as the flaps go up and down, the rod not only goes fwd/aft, but also moves outboard/inboard. The hole ends up being this weird ellipse shape. Picture an oval thats partially on the belly and partially on the side.
I hooked the flaps up one at a time and moved them by hand. every time it rubbed I marked with a sharpie, took the rod back out and hit it with a file. The holes will end up being bigger than you would guess at first glance.
You may not want to drill into the side skin, but you’re going to have to. The good news is the flap pushrod hole gets covered up when the flaps are up. Good for 10kts….at least.
Here’s pictures of mine.
View attachment 49106
View attachment 49107
The rod bearing attachment to the flap in post #2 is non-standard, although probably preferable to protect flap rod attachment in the case of a bearing failure. Plans built lower rod bearing attach:
https://www.aircraftspruce.com/catalog/appages/auroracm.php?clickkey=3009380
If the bearing fails in the one above, it could possibly slip off the ball, allowing that flap to retract, although I’ve never heard of that happening, and it’s the one I used. I wasn’t wise enough to consider this post 2 attachment when I was building my -6.