[Stocker]

FWIW, I have owned my K20 for 47 years and during that time it has had four different sets of wheels.

1) The stock 16" lock-ring wheels.
2) Aftermarket 15x8" white wagon spokes.
3) Aftermarket 16.5x9.75" chrome wagon spokes.
4) Ford (Accuride?) 16x7" steelies.

I couldn't say if the stock wheels were hub-centric, but none of the others were. The truck has been heavily loaded more times than I can count (up to a verified 3 tons in the bed), with no wheel-related problems ever.
I agree with Jerry Moss, hub-centric rings are absolutely not needed in your configuration.