I've got a working demo pinging every 1ms using 2 simple transducers. The object is 10ft away.
To summarize: First you need to know how many integer feet away it is.
Sounds like I cannot use the same hardware you have with 2 units, sender and receiver.
My goal is to double my distance, as you said.
With a Quadcopter, this S/R method allows me to put the receiver on the ground away from the noisy motors and blades.
Again doubling the distance, that's >x4 compared to using a single sensor in the air.