I can mount the sensor on a scanner servo but it would have to be sweeping constantly and probably wear out the mechanical servo quickly.
A Chinese menu of approaches. Take you pick
(1)You can always use a decent metal gear servo rather than plastic. The torque requirement is very low so lifespan should be OK.
(2)When using multiple sensors determining which one is easy. You can only fire one sensor at a time to avoid cross talk. As a result you know the source of the return signal even if the returns are OR'ed.
(3) Consider using a shift register to 'recover' other IO pins, thus making more available for Ultrasound.