Yeah, Dont do it. I probably put the first trolling motor ever on a kayak back in the 1982. At least I couldnt find anyone else who had tried it. The wheight and storage problems of the batteries needed to run all day is the problem. Try putting and eighty pound bag of cement on the back of your kayak and see how tippy it gets. Then try paddling 5 miles back to your car with that eighty pounds slowing you down and the motor dragging through the water. You will have to paddle on the days you use up all the elctric energy and are far from your home. Aluminum L channel is the only way to go if you insist on trying.
Kayak & Canoe Outriggers
Kayak Motor Kit