Can any describe what the impact would be of having the cplane 15x10^6 units (feet) away from the world origin? Will the display get corrupted, especially in render mode? Will booleans have any additional trouble? Does it matter what the modeling units are (in Settings)? Where/how do you check and adjust where you are operating in Rhino’s numerical domain, assuming you want to be somewhere in the middle, and not at one edge risking numerical precision problems?

https://wiki.mcneel.com/rhino/farfromorigin

Yes it matters. Rhino stores geometry in the units used for modeling. Change the units in Options > Units > Model units, select the rescale option, and the numbers used to calculations and storage for the geometry change. Calculations and storage use coordinates in the world coordinate system, not in local Cplane systems.

Possibly. Display problems caused by too far from the origin are a recurring topic in posts here… Display calculations in the GPU use lower precision than geometry calculations in the CPU.

That depends on the size of the details in the geometry.

Thanks for that synopsis. I think I am seeing bits and pieces of all of that. I need to figure out a work flow to model near the world origin.