What I did
Since the wing skins are .032", I chose to countersink all my -3 rivet locations, and actually, I did not use factory skins, but made my own full length .032" upper skins with no mid-span splice. Since I countersunk, I had no need to dimple any of them in that area. Vans typically gives the option for the pull rivets for ease of installation due to the close rib spacing and access. I had no problem shooting solid rivets in every hole. If I were going to dimple the skins, I would dimple them all separately, as well as the ribs.
8A7 / Advance NC