For various reasons I have revised the plan, making it even simpler than before. The layout will consist of a simple straight shelf section, instead of being L shaped as planned. I guess I am still a little intimidated by myself having to give up on the "individual tie plates" approach and want to keep this next project as simple as possible. So here is what it will look like.
It will be a oval with a siding for meets, and some hidden staging tracks behind a mountain crest. As said before - designed for rail fanning and nothing else. The relatively tight curves are hidden inside tunnels. The other leg of the original L shape might easily be added later (as indicated by the dotted track that runs "off shelf"). The shelf dimensions are partly given by the available space, but also by the dimensions of a standard plywood sheet. So for reasons that will be revealed in future posts, the shelf will actually be 341 centimeters long (and not 330 as stated in the figure above).
Next time I post anything here I hope to have pictures showing some real progress.