Per the manual, I marked and trimmed the leading edge inboard end. This is a little more difficult than the TE because you have to work around a tapered curve of the top side of the airfoil. A good long flexible straight edge helped plus a lot of eyeballing. I marked and cut through the fiberglass skin on the top side first but not all the way though the foam (sorry, forgot to take pics of that process). Then flipped the wing over and marked the bottom. You can see my modified square I used to get a good straight line, perpendicular to the spar (pencil line in skin). Bottom line perfectly matched the front!. I cut through the bottom skin and removed it. Then cut through the foam, careful to not cut the rudder tube. I then used mt drill bit tool and an another 3/8" bit set to 1.25" and in about 20 minutes routed out the foam. I then marked an cut the mounting bolt access hole on the bottom per the book, and lined it with BID. First time doing a lay up like this and it came out pretty well. Next will be flipping the wing back over, making the top mounting bolt access hole, and adding the reinforcing UNI over the mounts. I am then going to set this wing aside and skin the other and get it to the same stage as this one. Then I will set them up side by side in my garage (more room) and do the inboard lay ups at the same time and mount the winglets at the same time. The fuse will move to this area and I will start on it.