You adjust your zone, evenly, for both teams!
My interpretation that seems to work is to go a tad higher and wider. Not much, just a couple of inches.
Those other standards you listed are for regular games, NOT lopsided games. But in the lopsided game, you need to expand a bit to keep things going.
We have a lot of D III around here, and the pitching isn't so hot, so the games tend to have a LOT of runs.
Anyway, I have found that is blowouts, neither coach seems to mind if you expand your zone a little bit, as long as it goes both ways.