Not sure I would go with a trolling motor, batteries are heavy and can die quick if not charged 100%. By time you add the battery & TM, it weighs more than a small outboard.
I would go with a smaller outboard, no heavy batteries to lug around and you can use a smaller gas can. You can also move the gas can up front & even up the boat a little.
Is your boat a planing hull or displacement? I'm not expert but if it is displacement, you can probably get by with a smaller engine (3-5 hp)since you are only going hull speed anyway.