Years ago I bought a ten foot utility trailer with a 3500 pound Hayes single axle, to use at work and elsewhere. Could not find one this size with electric brakes, so I eventually researched and discovered that Dexter brakes and hubs would fit it perfectly, and best of all were in stock locally. Did this mod one winter and it's worked fine ever since, and I'm still on the original brakes. I don't know if this would be cost-effective today, but it may be an option. I remember it being a fun project; possibly more so because the dealer assured me it would never work.