I would like to add a ball-valve right after the brass elbow on my raw water hose (before my Flush Pro). This will make it easier to add antifreeze in fall - eliminating the need to climb under the boat and tape up the water strainer. It will also allow me to shut off the water flow if needed to do any on-water repairs involving hoses, impeller, etc. Has anyone added one? What size valve did you use? Dave