Dani
I have waited until until other posters have given their ideas so now I will share mine....Go to a car wrecking yard and pick up a axle stub enclosed bearing as my pictures show......clean all grease out and oil with gun oil....have a plate cut out at a machine shop, this could be any thickness.....bolt plate to axle brake mounting flange where the brake shoes used to be mounted ....make a pocket in a piece of wood for a base to seat the mounting flange....
I made mine just like this except I machined the plate, It has been in use since 2012 and I love it...
Overall cost should be low, the plate will be the expense....Maybe your mate can come up with something to help....