Thank you very much. Better more detail than less.
And anyway I can go back to this when necessary.
I have a non-gripped 5D3 so I believe the problem will be a little less.
I am aware of possible Markins head limitation and when I use it I will be very careful.
Right now I (think I) have no access to an RRS representative in Europe but I have already ordered the Kirk plate and replacement foot so that's it for a year.
I understand that eventually the correct thing is to use a specialized head but the use of this lens will be mostly for:
1. Sunsets/moonrises/sunrises (with extender or not)
2. Wetlands visits. This will be a first!
Lens arrived on Friday 21st. After a rather unfortunate choice of place on Saturday
I found the correct spot next day (full moon day) and that day was rather a success.
Since I did not have either a lens plate or a replacement foot I reverted to my old Manfrotto 055PROB with a Junior Gear Head 410 head.
Now the advantage of this head is that the plate can be used either with a 1/4 inch or a 3/8 inch screw.
I used the later and the lens was steady (with the help of mirror lock and 2 second delay anyway).
This combination is perfect for the sun and the moon but is useless otherwise.
So I am thinking of Markins as a compromise for now.
(Another choice I am contemplating for the next year is the replacement of M20 with an Arca Swiss Z1)
But first I need to test the combination...
By the way isn't the use of glue bothering you with the thought that you are somehow bound to that choice?
Is its use permanent?
Again thank you very much for your response.