Reset the camera to 2K (2048 * 836) and render the same set-up, the map no longer fits (it shrinks (or more likely stays the same scale and the character layer has been zoomed to fit the new camera size)).
Tested in ASP 5.6 and 6.1 = same result in both.
Pity as I had a really cool look going

I'll leave a question in scripting to see if there is a work around.
Rhoel