I think it will be up to you to build one of these retro reversible gear boxes for a large cargo bike. Maybe a long box bike that can drive 450lbs total combined weight up your steep hills in Vancouver. I still have not found one of these retro gear boxes that has actually been built.
Epicyclic retro-direct 2 speed transmission
With 7500 rpm output you will need a lot more gear reduction (like 13:1 total) to keep it down to about 13mph on a 9% grade. I don't know what the long road grades are in the hills there, but probably not more than 10%? but even that would be quite a low gear with Canadian legal power.
Maybe it can be done with two motors, making it illegal only when you need to turn on the second motor. Never being able to drive over the speed limit on flat land should be taken into account by the laws.