People ride 400k's all the time, but they're usually loops or out-and-backs. If you do it as a one-way, you have a possibility of having headwind the whole way. And on the 400k's, the stopping points are pre-defined, so you don't have to worry about where you're going to find food or water. And, in this area, they're on rural roads where you can go miles without stopping, not sure how that compares to the countryside up there.