The rear spar bolts were finally inserted into their holes after many hours of attempts. I bounced up and down on the wings attempting to move the wings down to align the holes. The fuselage bars were spread farther apart, which seemed to help move the rear spars down a little. I made a 5/16'' bolt holder out of scrap aluminum and that helped position the bolts into the holes.
The first bolt took almost four hours to get all of the way thru. The next problem was to determine the correct number of washers, as the bolt length called for was too long. I ended up adding two and a half washers on each bolt. Castle nuts were screwed in place and the bolts had to be adjusted so that the cotter pins would be able to go into the holes in the bolt heads. -208 cotter pins were used in the bolts.