Using optocouplers at the end of a twisted pair
Opto Isolators are non-ideal in many ways, including speed and difficulties with charging the driven cable capacitance. 

You would be better to consider the new generation of digital isolators such as those made by TI.
For example if you are isolating at the send (Tx) side, the TI ISOW7821 is a two channel isolator that can be run from a 3.3 - 5V supply. It's good for 100Mbps so should be adequate for your 10us pulse/timing requirement. If you can't find a 3.3-5V supply then you'd have to generate this.

   

This application shows a CAN Bus being drivern, but the isolator could be used to drive your signal cable with almost any configuration you want.