Two things to consider. One is rather important, the other would be a deal-breaker.
What kind of suspension do you have? Do you have independent torsion axles or leaf springs with a tubular axle ?
If you have independent suspension, check the 'drop angle' of the trailing arms. More angle will give you more suspension travel, but may make the brakes act funny. The arm that activates the brakes is curved around the front half of the backing plate. When mounted at an angle, a bump might cause the magnet to drop down a bit, activating the brake in the process.
If you have leaf springs with a tubular axle, the brakes would be mounted level, but the deal breaker would be whether there are mounting plates on the ends of the axle. (you need those mounting plates on the independent suspension, too) There should be a square plate that is maybe 4 or 5 inches across that the brake backing plate would mount to. They can be added if you don't have them, but it's not that cheap.
One last thing to consider: when you have electric brakes on a trailer, you need to have a controller on the tow vehicle. Not all that hard to mount and wire, just another expense that you might not have thought about up front.
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