I have a reversible pump that's feeding a pair of bags. one is under the Port seats, the other is under the port bow seat. I had put in plastic manual ball valves to switch between filling/draining each of the bags. (it just worked best to do them independently vs all at once and sometimes I want one or the other and other times both.)

So I had a couple of motorized ball valves that I used to automate this process. they open/shut by reversing polarity. Pretty easy to wire up to a DPDT swtich (just like the wiring for the pump itself).

Here's a video I did on the install: