Jeff, my first thought as I was reading your original post was to find a way to suspend the sporran from braces. This seems like it would transfer the weight of the sporran to your shoulders vs the kilt and would provide a very elegant solution. You might try attaching a D-ring to your braces,( these could be sewn in very easily,) just above where they connect to your kilt and then use snap hooks on the ends of a mini- strap if you will, thus going from D-ring to sporran to D-ring. Your waistcoat would conceal the D-rings and snap hooks. Good Luck,
David