How can I connect bananas to Wilson speakers?

Hello, I hava a pair of Wilson Audio Sophia 2 speakers.  They use heavy duty brass nuts that screw onto the binding posts to secure speakers cables with spade terminators.

I am interested in using speaker cables with bananas on the Wilsons.  I won't bore you with the why part of that, but I am looking for a solution to connect the bananas to the Wilsons.  

I understand that there are banana to spade adapters available, but I was hoping for a better option.  Does anyone know of a high quality aftermarket binding post nut that can replace the stock Wilson nut, and will accept a banana? The idea here is that I can simply unscrew the Wilson nut, and put on the new, bananan accepting nut, and not have any invasive change to the speakers.

thanks!