What's wrong with using a Zoeller with a built-in switch?
I simply do not believe that for ordinary use the switch is a problem. My last Zoeller lasted 16 years and was still going (but rusty) when I replaced it.
I would only consider a seprerate switch for a sump pump that was running 24/7 i.e. a basement with serious water issues. But for most of us, when the sump runs only when it rains, the built-in switch is fine, depsite what other posters might say.