You're going to need scuba gear if you want to go under Lake Superior. The extra drag moving through the water will definitely affect your range as well.
Based on what I see on A Better Route Planner, there are Superchargers available regardless of which route you choose. If you're planning to remain in Canada for the drive from Victoria to Ontario, then the northern route around Lake Superior would seem to make more sense. That would end up being roughly 4324kms of driving. But dropping down into the US and driving across the northern states and taking the south shore of Lake Superior seems to have a higher density of Supercharging stops available and would end up being roughly 200kms shorter at 4112 kms.