Since I only typically need to switch the controllers a couple of times per year, startup and blowout, I used a very simple, manual mechanism that isolates the controllers.
Each controller is in its own enclosure with wire bundles that come over to the separate ‘switch’ enclosure and are terminated on phoenix plug blocks (e.g. 1792388).
The valve wire bundles come into the ‘switch’ enclosure and are terminated on phoenix receptacle blocks (e.g. 178867) screwed to the internal plate.
https://www.phoenixcontact.com/en-pc/products/printed-circuit-board-connector-mvstbu-25-16-gb-508-1788677