Now for the moment of truth.  I was stressed about this particular evolution as I have seen where other builders have had trouble with this.  Since it is one of the last evolutions for the rudder, I hate to wreck all my work up to this point.

Per Van's instructions, here was my method for riveting the rudder's trailing edge:

1. Set every 10th rivet by back riveting just enough to hold the rivet in the hole and checking for any developing deformities in the trailing edge.
2. Go back and set every 5th rivet, using the same method called out in step 1.
3. Set all remaining rivets, using the same method called out in step 1.
4. Flip the rudder over (carefully) and further set rivets (factory head side) to approximately 70-75%.  This allowed all the factory side heads to be fully set in the skin dimple.
5. Flip the rudder over again (carefully) and fully set all rivets by back riveting.  It took a fair amount of "hammering" to get the shop head fully set to where I was happy with it.

Now the real trick I found with riveting the trailing edge is to get the back rivet plate to be solid against the rudder skin.  Since the rudder gets narrower as you go to the top, the back rivet plate will not set flat against the skin as you progress down the rudder.

I used several standard carpenter shims to shim the back rivet plate until it was firmly sitting against the rudder skin (both axis's up-down and forward-aft).  The back rivet plate is pretty short so it had to be "adjusted" every couple of rivets.  The key I found here was to ensure that the back rivet plate does not "teeter".  If you are not careful when you shim, the plate will move when the rivet hammer strikes the rivet.  What I found worked about the best is to put the carpenter shims directly under the line of rivets on the trailing edge to be back riveted.

NOT SHOWN:  I used a couple quick-clamps to minimize movement of the rudder assembly.  Once shimmed, you do not want the back plate or the rudder to move.

Just a close-up of the same picture above.  The right side in this picture looks like it needs to be shimmed up prior to riveting.

After I completed the second pass, the rivets were beginning to look pretty good.  I again, took another pass down the trailing edge on the shop head side of the rivet.  It only took a couple of rivet hammer strikes (Sioux 2x at 45 psi) to fully countersink the shop heads.  One reference describes that the shop heads would look like a "acorn sitting in a dimple".  After this final pass, the shop heads sat very flush and almost filled the dimple on that side (almost, but not quite).

Van's instructions state that the trailing edge should not vary more than 0.100" from a straight line.  Visually, I could see only a very slight waviness on the trailing edge.  I put the straight edge (aluminum c-channel) and measured the gap (I used the light to demonstrate the waviness for the picture).  The measured maximum deviation from a straight line was measured to be approx. 0.050".

I CAN LIVE WITH THAT!!!

Very happy with how the trailing edge turned out.  Not a "Grand Champion", however, I don't want to spend the next 10 years building this thing to take out the 0.050" deviation.

Looking on the internet, I came across another builder's tip that looks like it would work really well.  Instead of back riveting the rudder's trailing edge, he modified a die set to squeeze the rivets.  He claims excellent results.  I have attached a link to that information.

http://www.matronics.com/photoshare/jimnbev@olypen.com.07.29.2003/