I drilled out a few rivets because 1) I was a bit careless and 2) I was dull (rivetting nutplate rivets without nutplate!!!)
As the instructions say you can back rivet everything apart from the nutplates.
The only thing I found a little odd was the rivet call out in the corners. The metal thickness is the same but there are call outs for AD4-6's next to the weldments where access with a normal back rivet set is not so easy.
So I tried an AD4-7 in this location and it bent over slightly because I could not get vertical pressue with my normal back rivet set. So I went back to AD4-6's and they set just fine. I suppose if you have an extended straight back rivet set the 7's will be OK.
Impressions: Dimpling stainless steel with the DRDT-2 was a joy and I was very pleased with the overall finish. The really neat thing after the wings is you only have to do things once!