Years ago as an initial experiment I ran electrical SPDIF (75 ohm coaxial iirc) through a set of (800 or 900 MHz) "video extender" units and found it worked pretty well, I simply had to change a resistor on one end or the other to make the levels appropriate. The bandwidth requirement is comparable, maybe even a bit lower, than composite video.
However it cut out as soon as the microwave in the kitchen adjacent to the lab was turned on. Cut out cleanly and resumed, but that was unacceptable in the application under consideration.