Starting with a fully charge LiFePo battery, and a 100 watt panel, should be a no brainer. I think I was only using the #2 setting on a Minn Kota 35 lb motor, and cruised steadily at speed (2 - 3 mph) for about 5 hours. LiFePo batteries have a greater capacity, and with ~3 Amps from a 100 watt panel recharging your battery, think you should get what you want. (Panels never provide full amperage in a moving vehicle.)
Key issue is to keep the battery (and its' weight) towards the front of the canoe. Placing the battery near/under the front seat and insulated it from any metal contact, your canoe should then "glide" over the water. As the LiFePo batteries are so light, may have to place it closer to the bow. My Scanoe didn't even leave a wake at the lower motor setting with this set-up. Don't move the battery towards the back of your canoe. Without the battery weight far enough forward to counterbalance your weight, speed goes down, and battery draw goes up. Don't be afraid to try moving the battery around to find the "sweet spot". Harbor Freight has Jumper Cables, and you can use heat shrink tubing to make a custom wiring harness once you find the sweet spot.