The leading edges and hinge caps can be sanded flush to the skins (use masking tape to protect the skin!). I usually wait until later to final sand the hinge line bevels and leading edge radii.

There will be another cut required on the stabs before the root ribs can be added. The root must be cut at an angle to match the fuse sides near the rudder post.

Re-assemble the stabs, carefully aligned back into their shucks.

The detail drawing of the stab layout will show an offset at the leading edge that can be transferred to the top of the shuck. Another way to layout the cut line at the root is to use one of the rear fusebox top or bottom pieces. This can be carefully placed on top of the cores so that it's centerline (fusebox top will have this line) is parallel to the stab root edge. Notice that I drilled a small hole near the front of this piece to see through to my parallel line on top of the stab shuck. Move the wood piece so that it begins the cut right at the trailing edge of the stab root. Now mark this line.

Cut along this line on each stab and shuck assembly. Be careful to keep this cut perpendicular to the top surface of your stab and shuck assembly.

Afterwards, the stab tubes can be inserted and we can visually check how well the cuts match the taper angle of the fusebox top piece.