How would I generate a new object based on player location?

I'm working on a project using the Roll-a-ball tutorial project as a template. I removed the walls and the pickups (along with any corresponding scripts), so now I only have the player and the plane serving as the ground. The only functionality is the player moving around with the camera following it. I am trying to write a script that would generate a new plane identical to the one at origin whenever the player reaches the end (outer 10% or so?) of the current plane. The plane should be generated in the direction the ball is currently rolling, and the ball should roll seamlessly from one plane to another.
I am pretty new to scripting and generating objects using scripting, so please prioritize using code that is easy to understand rather than the most efficient.