You may find that your trailer has Dexter axles, just because the axles shipped without a braking package does not mean that they could not be added later. you may find the tabs already welded to the ends of the axles to accept brakes.
Your choices would be electric or hydraulic depending on your choice of backing plate and still use the same brake drum for both brake types.
Have a look for the square tab which will have four holes drilled into it, this is where the backing plate attaches. If you have no need for a tandem axle trailer offer it to a forum member who lives close to you. You'll get much better than scrap price with no deduction for tires.
Trailer can be registered as home built, just by making a few modifications.