I have added comment to that Jira as it was closed as WILL_NOT_FIX.
A friend suggested I just call my own server and the resulting page will be what I was after (loopback).
Is there any reason this would not work.
Seems to solve the headless problem and seems reasonably simple...
Seems like I will have to pass params and a conversation ID to ensure the loopback has the right variables to render with when it comes back in....
It'll work, probably the best solution right now.