Here are a couple of things to read.
Trade magazine
A Mounting and Balancing Act - Retail - Modern Tire Dealer

Dial indicator with pics
Measuring Wheel Runout

If you want to check the rim , the tire should be off and the rim mounted to the truck, slowly turn the rim and test for both runouts.
The hub/bearings could also be suspect.

I'm old school so I won't cross rotate any tires.
They only get moved from front to back or back to front same side.
In other words, they always rotate in the same direction.
These days the tire manufacturers say it doesn't matter, but on my vehicle it does, I don't cross rotate.

I also don't rotate tires unless I see some abnormal wear, usually the front tires show first.
It seems to me you are wasting a lot of time, energy and money by rotating your tires so much, but it's your call.
You may be spending more money with all this balancing stuff than you would by never rotating and just replacing the tires when needed, even if it may be a few thousand miles early.