Since I rarely fish from the front of my boat anymore I have my transducer portably mounted on PVC pipe I put over the side whenever i need it. I mostly LL troll and fish out of the back of my boat.
I suggest the trolling motor. If you fish channels, this will tell you when you are leaving or entering. Lets you know wheather to speed up or slow down. I have one on trolling motor and one at the rear of the boat for when I'm running..........works for me.