I have a Road Master Even Brake. This is the second one. The old one was 12 years old when the air compressor quit compressing air. Road Master has a customer loyalty trade in program, which at the time was about 25% off a new unit. The newer one is much better in deciding when to brake. Have had the new model for 3-4 years with no complaints. If you flat tow a rig with a off road based suspension and tires, use the "less" settings.
Also consider limiting the front suspension rebound. I have a pair of limit straps on posts with quick release pins to keep the rebound down to about 6". I had to brake hard, like standing on the pedal when a box truck pulled out in front of me. The 14" coilovers unloaded, the tow bar pivoted up and broke off the mounting tabs, which allowed my rig to run into the back of the tow vehicle, about 4' up. Insurance said it was a mechanical failure so no fault and paid for the $12,000 in damage to my tow vehicle, and a new tow bar. Trail rig was unscathed. The limit straps keep it from reoccurring.
If you use a supplemental braking system, you will also want to ad a 12 volt charge wire to the wiring to keep the toad vehicle's battery charged on long hauls.