Hi Zeke, I should have clarified my words a little. I was taught not to jam the heels down, but let my weight sink naturally in the heel. As for the majority of the ball of the foot - the weight should be mostly balanced, with a little more on the ball or "evenly" across the foot. You describe what I was doing some time ago--placing your weight on the outside of the foot.
The stabilizers of the ankle are small intrinsic muscles of the foot. The calf muscles are larger and aren't involved in such small adjustments. The calf (gastrocnemius) is responsible for pushing off on the foot as in rising up on your toes when your knee is straight. The gastroc attaches to the heel bone through the achilles tendon, and with your heels down, this muscle is being elongated as we ride, not contracted. The soleus muscle run alongside the gastroc and because it inserts below the knee joint, is probably more in use as we ride because our knees are bent --it would be in a static or isometric contraction.
I am just saying that using the bigger lower leg muscles may add to your overall lower leg gross strength, but for stability purposes, it is a re-learning your foot muscles need to do with the proprioceptors, in order for your ankle joint to become more stable.
Even towell crunches would be useful....place a towell on the floor in front of you, and sitting on a chair, pull and bunch the towell towards you until the towell is all under your feet. You'll be surprised how tiring this can be. Be well.