Given there are steam modellers on here, there is a new manufacturer
who seems to intend to focus on this era for their models, and they
have announced their first models - single sheathed box cars. These
are plastic models, and will be available as RTR and kits.
ATSF Bx-11 class
ATSF Bx-12 class
ATSF Bx-13 class
RI tall Pratt truss box cars
Don't know if these made it into Canada, but even if these aren't
appropriate they may be worth keeping an eye on for future products.
No prices or order details yet.
https://www.prototypejunction.com/2019/12/project-1-atsf-bx-11-12-and-13.html?m=1