Here are some early tests done today in the 3.07 build:
This shows how a render target can be attached to a texture input in 3.07 (via a new built in render job texture node - it doesn't save to file, but feeds back into the node graph). Using a group RJ group node in the current system, you can rasterize all the dependent RT textures (in the right order) before rendering the primary RT, all in one step from the node graph.