I know there's a downside with manual valves in place. Should you park the boat on the hard and (inadvertently) leave the valve closed the cold of winter will freeze the residual water within the hose below the salad bowls and bust the valve!

1. The boat's left in the water where there's less likelihood of
freezing, but without an external heater, is still a "potential".
2. Leaving the boat in the water without the valve also risks water
influx up into the 'salad bowls' diluting the antifreeze. In that
case a hard freeze could cause the diluted water to freeze and
possibly cause damage.
Having learned my lesson to close the valve AND vacuum the water out of the hose between the valve and salad bowl as part of the winterizing process, I'm inclined to install a manual valve at the thruhull.
Thots???
Thanks
Bill