I can how they can shoehorn it into MK but of course there would be issues with the path widths, which might not be a problem if they did not spend so much on the new queue for HM. They could find a way to maybe add a wide enough tunnel under the front lawn and graves of HM, maybe have the opening where the garden is at just inside HM's gates. They could use this tunnel as a way to transition between the Gothic revival theme of HM into the architectural style of the french quarter.
I do think that having it at FQ would be a little better because they would have the space there.