The pre-drilled holes in the wings (for the fillers) were reasonable close to the book dimensions - so I went with the pre-drilled holes. The location is OK but I should have used the book figures. Using the pre-drilled holes located the collars within 1/4" of the side of one of the tanks. Sanded the skins, smoothed the holes, vacuumed the tanks then set the collars in with flock. More work on the wong tips - removed the temp locating screws and sanded the joint areas. Then pre-wet the areas and laid up 2 strips of glass all around the joint.
Cutting the holes for the fuel filler collars and caps.
Fuel filler collar installed.
Applying the second strip of glass over the wing tip joints.