Information from Operation Grange and Bundeskriminalamt (BKA) indicates that Christian B. was living in the campervan at the time of the abduction.
In 2013, I had written in this blog: "Where was the abductor going to? [...] If we draw a vector, with origin in the sighting of Jane Tanner [very close to apartment 5A], and end in the Smith family sightings, we may infer, though not with absolute certainty, where the abductor was going to. What is in that area? A small house almost deserted, some apartments, a makeshift campsite for camping vehicles, the southeastern part of the small hill, many manholes, some rubbish bins, the Mata Porcas plant for treating wastewater, the sea."
" ...a makeshift campsite for camping vehicles ..."
The yellow vector has its origin in apartmen 5A and its end at the location of the Smith family sighting
A indicates the Dolphin restaurant, B to C is the camping area (all the basic maps are provided by Google).
Was Christian B.'s campervan parked in that zone (B to C)? It was a free parking area. If so, neighbours or tourists maybe have seen it. Even maybe they have pictures of it.