Actually Patagonia’s blackhole 2/6/10L pouches would work better. I think 6L is the best. It can be accessed while riding. Because of double zipper and different closing system then the north face.
Good strap points circled.
and from the bottom easy attachment to head tube with extra strap.
Got any pictures of how you're mounting it and what hardware you're using? (also @ThePeginator )