Made some progress, but AJAX is putting the browser in an infinite loop.
Added some hacks to help with the Owasp CSRF guard.

Need to make sure that I am not disabling CSRF protection!
Should factor out the hacky code into plugins.
Modify cookie paths that may be sub-paths of the proxied path.
Intercept Ajax errors that occured because the CAS session was ended and redirect to the main UI URL.