Not necessary to use a Merlin/Panogear for this kind of picture ...It´s rather counterproductive using a merlin with a fisheye.
It´s base is so large that a very big Nadir-hole occurs.
Also in terms of speed a manual head is preferable.
Unless your setup is such that you cannot reach the pano head to reposition it - shooting on a pole, and so on.
Using a fisheye on a pole the Merlin´s big base gets even worse. I tested it years ago: the bigger the head´s base the lesser you see from the ground - which is quite logic.
And that´s definitely not what you want using a pole . . .
No - for shooting with a fisheye on a pole better use either a motorized head providing a rather small Nadir-hole - Seitz, Dr. Clauss, Panoneed - or use a manual head with the camera set slightly angled or just a ring and put marks on the lower part of the pole for orienting during spinning the pole. That´s common use.
The problem with a manual rig on a pole is shooting the Zenith - but there are tricks which help here.
Believe me: using the merlin on a pole with a fisheye really is suboptimal . . i realized that by doing