Depends on the height of the mount etc and how low to the horizon you want to see.
Is there a reason to have 2.1 m high walls?
This will mean a higher pier.
The roof isn't there most of the time so you dont have to duck.
Even in the day I can stand with no problem becaise the bottom plate of the trusses is higher than the side walls. The only ones that are lower are the end ones and these are the ones I grab to roll the roof off.
My walls are 1.9m high and I have a roll off pitched roof. I can see down to about 20deg alt in 3 directions (not the direction the roof rolls.)
The pier is about 1 m high with an EQ6 plus a standard pier extension to give me the attachment points.
The pic shows it. Sorry about my daughter in the image but she was playing the clown.
