I have been pursuing a similar build stratgey. Hills are not so much the problem day in and day out, but when we go away to go trail riding, they always crop up. So I have been going around with steven at Grin and am alomost done with build spec. All I have to do is pull my cranks and measure the BB spindle end to end to get the right torque sensor into the order ...

What I really want is teh complete Bafang H400 Solution as seen here: https://www.bafang-e.com/en/drive-sy...-system-1.html And I want to use their OEM FOC Sine Wave Controller as shown in this image:


What I like about this one is that there are four cables total. Two out one end, two out the other. Seems like it could lead to the sleekest seatpost install. Problem is I can't find a vendor who'll sell either the H400 as a kit, or the Bafang controller ...

I'll settle for a Grin square black box with extra leads theis time, but I'll keep pursuing the Bafang all factory system for a future build