Laurent, if you make the brake pivot on wheel mounted bolts
and attach a cable to other two mounting holes via some bracket
and install return spring it might work like Enduro rollerski
brake.

Pull the cable and brake will pivot and touch the ground w/ski still
having two wheels planted and rolling.

Ken, pulling the front, balancing on rear wheels, having poles clenched
in your hands still is fairly idiotic activity should be reserved for
Central Park only.