Breiti: I hate to archive this one so fast, but I checked and the cache is indeed gone. I still found a piece of the log book on the ground though (no signatures on that part).
Apparently, the area became too busy. Pizza boxes and other debris show that this area is used on a regular basis, which made me decide to not replace the cache container. One smart person even added a handwritten arrow to GZ, since there were two locations next to each other for which the additional hint fit.
When I arrived today for maintenance, a family took pictures and 10 minutes later, two young dudes showed up in a car. We chatted for a while, one of them knew the history of the plane rather well.
I still love the area, but it is more than an hour from my home and cache maintenance will be too high on this one.