I don’t think many forum members have walked this route. At least none who have been posting about it. When I walked the Camino San Olav from Santo Domingo de Silos to Burgos a few years ago, we frequently came across markings that showed we were on or near the Camino del Cid. It seemed to me that it stayed on the side of the road even when there were off-road trails that the San Olav tracks took us on. There is a good website with lots of info to get you started, and maybe some other forum members will chime in.