Uneven Thrust Loads on Needle Roller Bearings

[Madison]

or "How I Need to Make A Turntable That Will Not Bind."

So, I am in the midst of designing a mechanism that rotates about a vertical axis and I'm worried that the enormous attached moment arm will cause binding in this vertical pivot joint.

McMaster-Carr shows needle roller bearings that are rated for 1900+ lbs. of thrust, but I assume that is assuming even thrust on the washers at each end of the bearing. How does an uneven load affect the performance of such bearings? Are they a viable solution for this problem, or is there some other method that's commonly used for supporting vertical axles under torque load?

Attached is a graphic and, by circumstance, a vague look at the arm design. I hope it makes my concerns clearer.