Moving forward, To deal with the flat bottomed wing, I've added some strips of balsa to the underside of the solid balsa ribs. This photo shows only the balsa strips being placed down prior to gluing. I've always tried to follow my own mantra of "trial fitting before gluing." It may add an extra step and definitely slows down the building process, but I'm treading into new territory here and it seems to work best for me. You wouldn't believe how many potential mistakes I've managed to avoid by allowing for a trial fit before gluing. Even then, despite my best intentions, mistakes happen. In this picture, it also shows that my initial intentions was simply to glue them over the ribs and sand the front and rear ends down to blend with the leading and trailing edges of the wing. As you can see, it wasn't going to work too well. Thus, I knew I would have a llittle bit more work to do and would also have to beef up at least the leading edges.
The second photo shows me only using a small section of the balsa wood to determine whether or not this would be a good fit. When taking into account for sanding down the front edges of the added strips, it was a good choice.
I started out by using clothes pins to clamp down the added leading edge strips for an even surface between laminations.