The aft deck needs three holes cut in it for access or lightening or something. The location of those depends on where the horizontal stabilizer goes. With the aft deck clecoed to the longerons, I pulled the stabilizer down from the rafters and clamped it into position. Except for fore and aft, I made no effort to align it. I even left the protective bubble-wrap on.
The forward flange of the inboard nose ribs on both sides are flush with the skin. These interfered with the aft top skin, the turtledeck. The interference was small, maybe .090 spanwise and perhaps 1/4 inch long, and just on the bottom of the stabilizer. I trimmed these with a Dremel and a sanding drum, finishing with a small fine file.
Later, talking with my mentor, I learned that this is common on RV-4s and Rockets, too.
After clamping the stabilizer in place I measured where the various mounting parts will have to go and took this photo.
While I was tempted to bring the vertical stabilizer down from the rafters and clamp it on, too, I refrained. We all know where that would lead: lining these parts up and hanging the elevators and rudder. One of these days, but not today. Instead, I put the horizontal stabilizer back up in the rafters for now.