Many thanks to all the replies. Very helpful. Port side install for kicker turned out the best option.....depth sensor mounted on the port transom. Helm is on starboard, so port location seems to help the weight balance. Experimenting with using the 150hp to troll (it works OK, but 4 cylinders running uses more gas than necessary) and 9.9. I've settled on the 9.9; it causes a bit of steering challenge, but I'm used to that, and when trolling for salmon, a zig-zag pattern is preferred.
Topic #2: This replacement boat (18.5' G3) came with a Minnkota AutoPilot that I would love to be able to steer with while trolling, but I cannot figure it out, so it lays down mounted on the front. Another "winter project".
Thanks again. All very helpful.