Nice board! That KST shape will ride like a much shorter board when you're skidding low angle turns, but will rail with a tenatious bite when you set it high on edge. Your go at a 27/15 stance is very reasonable. I don't ride softie setups much, but actually prefer something a little steeper (30-/20-something) for freeriding / freecarving. In fact, if I were in the market for another softie setup, that or probably the BX in the same length would be a prime consideration.
If you try a forward stance again (2 runs doesn't give it much of a chance), rotate your highbacks parallel to the board edge if you can. They will be more effective with a somewhat more lateral leg motion. Also, as you rotate your bindings more forward, you'll notice your comfortable stance width will narrow in comparison to a duck stance. Last, don't pair it with "soft" boots or bindings.
If you're having upper body / rotational issues, you might be manhandling it in the wrong way, steering with your upper body. Try driving your knees / hips down a little more. That board should initate turns naturally, but you may have to be more aggressive setting it on edge. The manhandling part should be on edge pressure and driving through the turn. Let the board do its work. You just provide the muscle. Think, "strap in, shut up, hold on".