For the tri-gear, I dimpled per the instructions; but undimpled because it was not needed. It is clearly a flaw in the directions. There I am almost done with the Empennage and it is clear that they give less instruction as you move on in the project.
For example, look at page 10-27 rev 1. You will see the F-01414 Deck calls for a few flush 426-3 dimples; however, the bulkhead flange under them was never called out to be dimpled. I think you have to assume, that you have to dimple the flange. I also notice a lot of rivets are too short.
working on empennage
EAA Chapter 186