Ceramic low level cistern with back to wall toilet, boxing in behind back to wall toilet.

[agamemnon]

I currently have a twyford low level cistern, which is lever flush,I want a rimless back to wall toilet pan instead added to the low level twyford cistern, and I have been looking at the armitage shanks contour 21.  I wanted to ask, if an alternative option would be to box in just behind the toilet pan and and have the twyford cistern exposed rather than the whole thing boxed in. see original installation diagram and the new diagram.