If you need to put our extensions inside splitter panes you can do this with ease as illustrated in the Splitter - Resizing demo. I do not quite understand your concern. Please explain your scenario and the difficulties you have encountered in greater detail. I believe we will be able to offer a good solution.
In _Layout.cshtml, I have this layout defined:
I want a splitter between the "left" div and the "center" div to separate the tree view from the main content window. I am unable to do this because the RenderBody command is never processed and I get the MVC framework error indicating so.