I have mixed feelings about listing both the Panzermuseum and the SHP under the same page... They are pretty much separated entities and, most important, while the Panzermuseum is pretty much opened to the public, the SHP is not.
What about the tanks inside the base (Pz 39, G-13 and diesel Centurion), do you plan to list them separately?
I have given a lot of thought to this, and while I understand your point of view I think it is best to keep them all as one location entry, including the base tanks. I think the situation is not unusual, most collections have some vehicles that are permanently open to the public and some that are hidden away (sometimes the majority are hidden). For many other collections I list this is true - e.g. Bovington, Saumur, APG, Fort Knox, Kubinka, etc. In each of those cases it is also true that there are tanks on display around the surrounding military base some or all of which may belong to the main collection (and some whose ownership is unknown or unclear). In all cases I list these together.
In addition, there are practical considerations with regard to how the website and database work. Firstly, this way works well for showing multiple locations near to each other on a Google map (e.g. a main Thun location with multiple nearby sublocations) whereas trying to show multiple different locations on the same high level map will put them on top of each other. Also, it is easier to handle the regular moving around of vehicles, e.g. a vehicle moving from one Thun sublocation to another one. Finally there is just the practical consideration that people visiting an area, say Thun, want to know what's there and are not concerned about who owns each vehicle.
That's my current point of view. I'm happy to discuss it further, and certainly respect your opinion, but currently I don't see the SHP situation as being exceptional compared to other collections. Of course this requires that I make it clear what vehicles can typically be seen easily and which can't.