If the plumbing in your camper is set up anything like mine, you will need to pump the non-toxic antifreeze through the water pump so that will winterize the pump as well as the fresh water system. In my coach, there is a hose that is near my water pump that I can put into the jug of antifreeze and then suck out of the jug of antifreeze through the system. Not familiar with your camper so not sure if that is how yours is setup. Hopefully there another owner of particular camper will be able to shed more light on the issue.
Tom and Margaret
2014 Berkshire 390bh-60