Entrance pupils or nodal points

This is a test of my panoramic gimbal from RRS not supposed to be a 4 star image. Before this image was reduced in size it was 12 feet by 4 feet at 240 dpi. It was made of 30 images on a Canon 5D mark iv at 70 mm using a 70-200 mm is f2.8.
I have tried many methods from the net to find the nodal point, or entrance pupil, and I believe i am close to the proper setting. I found the tutorials weak on details especially when it comes to setup of the guides such as distance and separation especially on long lenses such as the 70 to 200. I have worked out some techniques that seem to help but at longer telephoto ranges it is still difficult for me to find the exact nodal point.
I understand at telephoto distances the proper nodal point is much less important unless there is an object in the foreground...but it would still be nice to have the proper settings.
I have found three partial databases listing various size and make lenses but when I find lenes common to all three databases they each have different settings...frustrating.
It seems that with something as common as panoramas lens makers such as Canon would supply a database of nodal points especially for their zoom lenses. I can't find one and I am hoping that perhaps someone here may know the location of such a database or know a link where I could make inquiries at Canon.

Butch