If you only need transparency for fading in and out, you might be able to get around with a 2 pass shader that does a depth pre-pass. It won't give you 'true' transparency but it can still look really good! Basic concept is explained Here.
Ah it's a shame, I thought that the baked renderer maintained the draw order according to the hierarchy, but it appears that it does not. It might not be the right solution for your use case anyway though, since whatever sort order you choose would end up being constant anyway, and so it couldn't adapt to view changes.
For the group-layer method, you would want to use the GraphicRenderer's api to grab a hold of the group you want (either searching through the
groups list or using
FindGroup to find a group by name). You would then get a reference to the
renderer of that group. For BakedRenderers or DynamicRenderers the renderer will have a
material property which is the material used for rendering the objects in that group. You are then free to modify it's
renderQueue to whatever you want in real time.
(The TextRenderer for some reason does not surface it's material property, but the concept is exactly the same. In the meantime you could go into LeapTextRenderer.cs and add a simple getter for
_material and use it in the same way)