Just as you mentioned, I feed the rod through, made sure I had washers that could pass the bottle mounts, put the nut on. I thought about using pipe with another nut and set of washers but did not. I just held the rod in one hand with the nut and washers about 12" inserted in the seat tube, I then held the the frame at the top portion of the seat tube in the other. Next was a two handed power drop, almost like a baseball swing. Then I tried to follow through with the frame hand and with the rod hand I did like check swings for impacting. The threads on the rod did provide substantial area for gripping, if they did not I would have gone the the route of having the pipe sleeve and nutted washers to slam against.