Removed the temporary angle used to keep everything straight. The epoxy is holding the trailing edge straight.
Back riveted in the manner described in the instructions. Everything worked out great!
I decided to back rivet all the rivets, rather than flipping over the rudder and using the mushroom rivet head. I wasn't confident the rivets would stay put in the countersinks if I flipped everything over the way Vans suggests.
The trailing edge came out pretty dead straight, and the shop heads look pretty good.