Swany that is pretty.
Spas - We studied your mount and think it is perfect for the small to medium size stuff. For the big guns (4120 and up) we think some tabs on the top and bottom with a bolt going right through the fuse would work. So it would be just like your mount but it would wrap around the side and hug the fuse with a bolt through the top and bottom piece.

Next I'll take some pics of where my batteries live.

My goal was for the batteries to live on the fuse on each side below the wing. The problem with that is that it sux in knife edge. So the batteries have to live in the wing to keep everything balanced.