OK, I confirmed today that the wash down pump and AC share the same seacock/strainer basket. Our C28 is a 2019 with a Volvo D4.
The winterizing process has been easier than expected. UTube shows a complicated method of the removing hoses from the strainers. The tech used a five gallon pale filled with antifreeze with a pump and conical (universal) hose coupling to plug into the removed strainer hoses.....very complicated compared to just pouring antifreeze into the strainers with their cap removed while a second person activates the engine, water system, AC etc.
I also made up a short hose from Home Depot components to create a bypass for the water heater to winterize the faucets. That hose connects the inlet and outlet hoses to bypass the tank.