Methods and systems are provided for a vehicle towing a trailer. In an exemplary embodiment, one or more sensors onboard a vehicle are configured to provide sensor data, and a processor onboard the vehicle is configured to at least facilitate: monitoring a trailer sway of the trailer using the sensor data, based on one or more parameters of the sensor data representing the trailer sway and application of a band-pass filter to the one or more parameters; and mitigating the trailer sway, via instructions provided by the processor to one or more braking systems of the vehicle, the trailer, or both, when it is determined that the trailer sway of the trailer is sufficient to warrant mitigation based on the one or more parameters of the sensor data representing the trailer sway and the application of the band-pass filter to the one or more parameters.