I believe the position I placed my new fin box was somewhat of a compromise for a true foil setup (front bolt centered in the rear strap) unlike the slingshot boards which center the box completely.
I've found that I fly without a lot of front foot pressure which kind of locks the back foot in place, good for straight line but not for gybing/turns.
To correct this my first adjustment has been to shim the stabilizer into a more tail-up orientation. I considered washers, bits of plastic etc. but then realized that most of us have the ideal material in our junk bin: harness line tubing. I've started with a piece ~5/16" long between the tail piece and the stabilizer slid over the rear bolt. Tightened down I now have about an 1/8" gap.
Initial impression is improved pitch stability which has let me unlock some rear foot pressure and carve turns more from the front foot. I will cut a longer piece and see if I can find the sweet spot.