Ron thanks for that image again! Really helpful for the details
I should have done a more detailed sketch - but I have gotten a little sloppy over the years
I looked a little more at the image of the Vertical base and have noted a few things;
It doesn't appear to be a Nikon product,,, look and feel,,,
It appears to have four very thick rods, so it must have a ring behind the lens converting it into four rods from thee sockets, must have been for made for something else. Do you know if it is?
Nikon would never do that, IMHO much better with a single rod above the pentaprism - out of the way like the lens is designed for.
I will also do four feet, looks stable, and mine will be adjustable and spiked as mentioned, so no need to tuck the strap under the leg
Yes - I already have a similar level for the base.