mounting 2nd FishFinder
I went through this same issue 2 years ago. I wanted a second FF at the rear of my boat. I installed a Lowrance and all to excited to go try it out. I was quite disappointed with the results. I could not run both FFs at the same time. The cockpit FF was a Humminbird and both interfered with each other. Each worked great when the other was off. What I was trying to achieve was basically having a second monitor of my FF at the rear of the boat. I then installed a RAM ball mount and all the necessary connections to transfer the FF between both locations. This was ok but still was a pain because I needed it in the cockpit for depth, going to location, and locating fish. What I ended up doing was moving my mount in the cockpit to the center where I can see it from the back of the boat. I also upgraded this year to a Humminbird 1197c si.
I also have the advantage of having a TR-1 Gold system so I don't have to be at the kicker motor controls when fishing. I understand you wanting the FF at the controls and thought I would pass along my findings to help you make a decision. As for mounting the RAM system works great.