I'm trying to do the same thing. I have ordered the DC DC 48V to 12V 30Amp converter for my Minnekota EnduraMax 40. This motor will draw 42 amps maximum so could be too much power drain for the converter, on max throttle. I imagine my sweet spot for my canoe is around 250 watts, which would be 20 amps continuous, which the converter will handle supposedly. We shall see - just need to not max out the throttle! Its just for backup from my new sail rig.