colin.
One method I'v used is kinda drawn out but will give you a good patch. Like Delgato stated cut out the bad part clean by using a square off of your leading edge and cut a little beyond the broken area. While you have an opening that big, use that time to clamp up or get at the split leading edge and flow ca or aeropoxy in the seam and let cure. Cut some G-10 strips or balsa thats thin enough to follow the curve and glue it to the inside of each edge. Half in and half out. Will look just like your geardoor pockets. This will givew you something besides just an edge to glue your new wood onto. Bridge one side of your opening to the other with a piece of Tristock for a new leading edge and something to glue the front of your patch piece to. Make sure you use balsa a little bit thicker then the rest of the wing so you can sand down level. After you get that hole closed up, just a matter of sealing it with two part epoxy and painting. Good luck and let us know how it goes. Roy