Following a number of requests on the forums I started to develop this idea. It isn't perfect but it does the job and allows good views over yards, junctions etc.
It is basically just a junction camera, but makes use of an invsisible track object and invisible junction lever object so all you see is an unobstructed view of your yard.
The only drawback is that you can't see the object in surveyor either, however with careful initial planning it is not hard to keep track of where your skycams are.
First, select the invisible track object and lay a length across the real tracks in the position you want to be able to view. with the invisible track layed, you can see where it is from the spline end points.
Now select the invisible camera object ( it is a trackside object, like a speed sign or switch lever)
Place the skycam as close as possible to the middle of the length of invisible track you just layed (ie halfway between the two spline end points)
This makes it easier to find in the future. You won't see anything because the Skycam is invisible!!
Now use the ? junction naming tool and click on the spot where you just placed your Skycam. The dialog box should appear allowing you to give your Skycam a label. Pick something that you will be able to find easily among the list of junctions in Driver.
(I call mine Skycam 01 etc.)
Next select the advanced track options and in the set spline height box enter the height you want your cam - 20 metres works quite well. Now simply set the end splines of the invisible track to this height and this will be the start height of your new Skycam.
You can have as many Skycams as you like, and you can rotate and zoom the view freely just like any other junction camera.
In Driver, select the Junction view icon and click on the current junction name to get a scrolling list of all junctions. Find and select your Skycam to use it.
Enjoy