Finished up the bottom skin, which is great because now I can proceed solo for a while. Had a little challenge with how to set the center rivet in the aft most bulkhead. It sits between to other skins and the flush set cannot get to it. I made a little shim skin to place over the rivet and it set without any trouble.
Flipped the cone back upright and started riveting the side skin stiffeners. Everything is looking good so far.
The verdict is in on my new Boeing flush set with the urethane rim. It's awesome. I also got a red rubber swivel set. It's ok, but is tough to compress enough to keep the rivets from sitting proud.