Mex, I would expect a better range on canoe than on inflatable. Still, 40 AH is not much.
Canoes are more efficient under motor than inflatables. A dull bow of inflatable, a "hump" under water where you sit, and energy is lost in flexing hull. In unloaded canoe with 2.5 HP 4-stroke I can't open throttle more than 1/3-1/2 - it's already running 11-12 mph and 2 or 3 ft of bow is out of water, this is with me sitting in the middle and operating with tiller extension. Same motor on inflatable can't make more than 7-8 mph, and fuel consumption is much higher.