I just saw this thread and I'm glad to see others attempting to try the Dutch scapes. It needs to stay relevant and not become a thing of the past. I don't think there is anything wrong with making a twist on the traditional Dutch style by using hard scape but to see someone attempting to keep it traditional is encouraging to say the least. I agree with Phil about letting it fill in and grow for awhile before deciding on final plant positions. I spent my first years in this hobby strictly growing different plants with no concern with regards to actually scaping anything. I helped me just to learn certain plants growth rates and habits. Keep at it and don't be afraid to move things around once they grow in and place them in better suited places.