I'm not sure where the idea of radios came from... What I'd suggested was more like 30 feet (10m) behind the back of the troops. Easily heard, easily seen. Imprecise, yes, but what other way did they have?
Also, still very much in an area to be easily wounded.
The closer you are to the front, the better you can communicate... and the greater the odds that you do fighting yourself as well.
You can't have perfect communication and be completely safe from combat. Especially not in those times.
