Is there any chance a group of us (50 or more) could pay Mugen to create a custom battery. (Money no object type of design)

Similar to what planetf1is saying.
- Make the battery odd shaped, the bottom will have identical shape to the stock battery but above use a large surface area to keep the thickness down.
- Or maybe something more complicated that required changing the internal plastic molding to use up the space for the stylus.

I would pay up to $150 for a 2000 mAh battery that makes the back flush with the camera.