The motor should be sized to the length of the boat rather than weight. Minnkota motor selector does decent job but you need to remember that they are trying to make money - bigger motor=more profit, that tool has tendency to overestimate. As to power consumption : all of of the low end motors consume the same amount of power regardless of the power setting. You need to look for stuff like "Digital Maximazer" or "Digital Efficiency" - only these motors will consume less power at lower settings. And another thing to consider - drifting means hitting hard objects with your motor. The shaft of the motor will take most of the impact. I wuld consider moting the motor on "breakaway" mount and my prefernce here would be Minnkota over Motor Gude since their shafts flex. BTW these two are really the only chices letf in this field...