Are you using the integrated switch type, like this?
https://www.outbackequipment.com.au/...oaAspeEALw_wcB Or the separate float switch? I've seen a lot of comments on the Automatic type failing prematurely, and sometimes overheating, and I put it down to this one thing. The old float type just sat there, waiting for enough water to operate the switch and power the pump. Simple, but you need the space to instal them. The Automatic type works on a different principle--they actually turn on at regular preset intervals, and look for water flow. Including when you are out of the water on the trailer. So they are, in effect always on, and running dry when they do a water check. My original 1100GPH Automatic ran for four years, because I turned it off at the panel when the boat came out of the water. In fact, it's probably still good--it stopped working at four years, and I just assumed it was stuffed, fitted a new one, powered up, and the new one didn't work either. Found a wire off at the back of the panel
. Just something to think about.
I would have happily fitted a separate switch as pump, as we used on the big boats, but there is stuff-all space between the back of the tank and the transom on a Reefrunner,