I finished up all of the top skin to spar rivets while the flap was in the cradle. These were relatively easy to reach and buck. The wave that appears in the trailing edge when the nose skin is tightened up is pretty disconcerting, but it's a common occurrence, so I'm hoping it flattens out in the following steps.
The instructions say to flip the flap top side down and weigh down the skin and ribs to ensure that everything stays flat while riveting the bottom skin to the spar. If you don't do this, it's easy to introduce a twist to the flap. Putting the weights on the skin didn't totally flatten the wave, so I decided to just match up the trailing edge holes in the table (that I had drilled when drilling the wedge) and cleco the flap to the table. This flattened the flap 95% of the way there.
The clecos still needed some help to really keep the ribs and skin flat. I tried putting the weights under the skin and directly over the ribs. That flattened the ribs, but bent the skin too much and made it hard to flatten the skin to the spar for riveting. I finally settled on laying pieces of wood on each rib and then putting the weights on the wood. This was enough to push the ribs flat but also give me enough room to get my hand under the skin for riveting.
