I wanted the rear spar to be perpendicular to the bench top so I could flush it up to 2X4's without deflecting them outward. Used a 1X2 on edge, a 2X4 (notched for the front supports) and 2X2's spacers - all clamped together - to form a "seat" for the stabilizer. This configuration ensures that all downward loading from the straps will be distributed across the spars and NOT the skin.
Placed three premium pine 1X2's across top skin between rivet lines then applied four straps with light tension. Verified both spars were level along thier entire length (+/- 0.2 degrees using the short digital level).
Aligned the front spar pilot holes with the line on the front spar flange. Lined up the center hole with the center location marked on the spar. Used a square to verify the outside edges of the top and bottom skins were on planes perpindicular to the bench top. Made minor adjustments to make the leading edge parallel to the bench top.
Drilled center pilot hole through spar flange, allowing any minor tweaks to be made like turning a sled (think Rosebud from Citizen Kane). Pivot cleco can be seen in Image 2.
