Build the shelf up directly above the push point of the handle. That will minimize variations in your form from shot to shot. Same with the strike plate. Minimal contact point with the arrow, that's located directly above the depth of the handle helps overcome inconsistencies in form. BTW, moving the contact point forward or backward will have an effect of how stiff the arrow shoots. Move it forward and the spine gets weaker, move it back and the spine gets stiffer.
Nobody that I can find sells A&A fletch (except Toughhead sells really short ones). You have to cut them from full length feathers, but it's not that hard to do. You can cut a 5" parabolic into an A&A, but you'll probably end up with a feather slightly shorter than 4".