Some progress. For the trailing edge, I screwed a 1x3 to a 2x4. There is a 2x3 on top of the trailing edge with boxes of bucking bars on it for weight. Lets me push down on the leading edge while drilling. The first strap went on with just a little tension against the skin, and I put the trailing edge wood on next.
Then I put two more straps on.
Snugged them up a little more, then slid a 2x4 under them. I had an old flannel sheet to wrap it.
Pulled it down to here then it was easy to remove the spar clecoes from the front.
Tightened the straps a little more, the holes lined up, then I clecoed the forward skin to the spar. Next drilled into the ribs.
It went easier than I would have thought!