While this response is not specific to the bf17, I rebuilt our 1986 tf20 Bigfoot brakes
by replacing the entire backing plates, complete with all hardware, shoes and electronics. 4 bolts, and a wire splice,
much easier to do, and not much more than the shoes! They are common trailer components, auto parts stores may stock them or they are available online also.
While your at it replace the wheel bearings and seals, and if your brakes
are not smooth consider having the drums turned.
My mode is do it once and do it right, a 1886 trailer would appreciate the complete brake renewal.