Ok, I've done something I'm NOT really proud of, But I needed a solution for this problem.
My center leg is made from square aluminum tubing and the standard Ankle mount would not work for me.
In the pic you can see inside the Ankle and the square plates I added inside will cup the aluminum leg very tightly. I plan to add a slot in the plates so a fixed bolt in the leg will slide down into the plates and allow me to tighten the plates to the leg. It's hard to describe so I'll post more pics later.
The other pic shows the screws on the outside. Yeah I know what it looks like :o(
I'll countersink the screws and paint them white so they don't show as much.
Most of the screws will be up in the skirt and will not be seen, But I think the bottom 2 screws may show up.