I have a Lowrance HDS 7 Touch with LSS Ducer mounted on the transom. I am wanting to purchase some unit specifically for my trolling motor that has downscan, 2d sonar, and GPS. I do not want side scan with this unit.

What recommendations would you give me? I am not hung up on brand type. I prefer a 7" or so screen, but might consider a 5".

The best under $800 please, and why you believe this. I only vertical jig in a stained, shallow water lake (generally less than 13' deep). I am usually in 6/12 ft. of water.