I would double that range - giving it a 1Ω resistor. That also allows you to actually measure (and confirm) the stall current. Of course the resolution is cut in half, but that shouldn't be a major issue, and if it is, time for a higher resolution sensor.
You can also shield your hall effect sensor against any stray magnetic fields, though I doubt that to be an issue. Brushed DC motors are notoriously noisy (due to the brushes switching on and off the coils all the time), to filter I usually add three 100 nF caps to the terminals: one in between, and the others from either terminal to the motor's housing. That should take care of most of the noise.