Airing down—wheel size versus tire size?

I’ve heard that a narrow wheel relative to tire width is the “poor man’s beadlock.” At what point is the opposite true—a relatively wide wheel for the tire? I’m thinking about mounting a tire rated for 7-8.5” width to an 8.5” wheel. This is obviously within spec for the tires, but “spec” also isn’t running 18-20psi in sand for example. Do you think there’s a risk when airing down at the upper end of the tire’s width? Am I overthinking it?