NMorgan,
On the Z18, I mounted mine of the stepped up part of the hull starboard side. I have the Atlas Jack so the engine lower housing never blocks a side scan when the engine is fully down. I lose signal when the step clears the water going on plane but it has been a safe and trouble free location for me so far. I have a garmin transducer on the Port side and they don't interfere with each other as far as I can tell.