Virtually no one here uses motors so there won’t be many replies. Still, some of us have a bit of experience with small motors, even if not with canoes. 55 pounds of thrust seems like more than enough for a canoe. Think back to years ago when bass boats were moved around with motors far less powerful than that (I remember when 30 pounds of thrust was considered a lot). I won’t take the time to search right now, but I recall finding websites in the past that compared horsepower ratings with pounds of thrust. I’m sure you can find that info by searching online, and you might find such info handy.
I’m in the minority in this way, but for your use, I’d prefer a small gas motor over an electric. The overall weight (including the battery) of an electric motor is far greater, and the distance you can travel is far less. Also, your state’s boating laws are almost sure to require that the battery for an electric motor must be secured to the boat so that it can’t come loose, even during a capsize (I’ve never seen anyone obey that rule, but it’s one more thing to worry about). Remember too that many canoes don’t come equipped with enough emergency flotation to keep them from sinking after a capsize when something as heavy as a trolling-motor battery is attached… By my way of thinking, a gas motor wins this comparison.
I recall seeing square-back canoes that were rated for around 5 horsepower, but even 3 horsepower will move a canoe at a brisk pace, especially if the payload is light. And getting back to the weight issue, I have a 3-horsepower outboard that weighs half as much as a typical battery for a trolling motor, so it’s probably less than one-third of the weight of a motor-battery combo, but it’s much faster, and by adding just a few extra pounds in the form of fuel, it will be ready for days on end of normal use. Electrics have certain advantages (including price, in the short term), and that’s probably why most people prefer them (I was lucky - my 3-horsepower gas motor was free).